I know this is nothing new under the sun. But doing 20 lessons per day -and using reorder script- is a good pacing, I mean, in terms of avoiding burnout and level up lessons at a good pace, I noticed the previous lessons I had days without any lesson to do, and it’s a bit exasperating to want to study and not have anything. Maybe doing 20 per day and using the reorder script always have some pending lesson (mainly vocabulary).
What is yours pacing?
I use Lesson Filter to do 12 lessons per day. This usually consists of 3-4 kanji and 8-9 vocab (when available). I also tend to skip lessons a couple days each level if I’m busy or overwhelmed with reviews.
Unlike a lot of people, I don’t have a strict lesson number. I just do lessons whenever I feel like my brain can handle it. On good days (easy vocab or initial kanji batch) I will do 30+. My lesson count is usually 6 or 7 and I’ve been really forcing myself to do at least one set everyday otherwise I get lazy.
My level up time is about 10-12 days so it’s obvious I don’t keep a strict schedule but I don’t think I could handle 20 new items every day and stay sane.
Oh and I definitely use the reorder script so that I can start on my radicals and kanji. Then while waiting for those to guru I focus on the last levels vocab.
I use the same script, and do 10 lessons when I wake up (2-3 kanji, the rest vocab), and 10 before bed. How many kanji counts on the ratio between kanji:vocab total in my lessons, and some sessions I even have to do 4k:6v if I don’t have enough vocab lessons waiting. 
When leveling up I do 7 radicals, 2 kanji, and 1 vocab until I run out of radicals (20/day total), then start the above k:v ratio schedule.
Levels take me about 10 days this way, and I rarely have more than 40 vocabulary items from the previous level waiting for me upon leveling up.
I just take on as many as possible whenever they’re available, short of pushing over ~150 apprentice items.
I’ve been trying to do all the lessons as they come up. This usually means I get dumped on when Sunday morning comes around, but I’m trying to maintain full speed. I put my vocabulary at a very low priority when new lessons come in, so vocab slips occasionally, but I try to get to Apprentice III by the end of the day so I can hit Apprentice IV first thing next morning. This keeps things pretty consistent regarding SRS levels for radicals and Kanji. Like I said, I focus less on vocabulary and just let that follow its natural SRS progression if (i.e. when) I forget vocab terms.
Of course, this means I have slow days throughout the week, but I use those to focus on listening/speaking with Pimsleur as well as supplementing grammar through the Genki book.
I’m a bit obsessed at this point, but I don’t feel burned out yet.
I am doing 3 items per day. University is taking up most of my time but it’s not going to stop me from making progress in WaniKani, no matter how little 
Currently doing 10 a day with no add-ons or scripts, and trying to finish all reviews for the day when I get to them (or if not, doing at least 10 reviews before bed). I was doing max speed, but I need to balance WaniKani with actual grammar and stuff too.
I usually do lessons when I feel like doing them. I try to at least do 5 every time I do a lesson, which usually is not an issue. With radicals, I usually knock them all out together. With kanji, I do them in batches of 5, and if I feel like I will have some trouble recalling that last batch of kanji, I stop until I feel like I can continue lessons with little headache. In terms of vocabulary, it all depends on how “simple” the vocabulary is. If it is a bunch of jukugo words, I can easily knock out 10-20 vocabulary throughout the course of a day. Usually I level up between 20-25 days. It’s slow but I like this pace, and I’m not really going for tests like the JPLT. I am also not keeping up with any classes so again, I can set my own perfect pace and I love it.
Sorry for the really long post! I didn’t expect it to be this long!
I tend to vary how many lessons depending on what is in the queue. For radicals, I typically try to get all of them in one set of lessons.
For kanji, I usually limit myself to 10 per day since I find that I struggle on reviews when I do more than that since I’m learning twice the information, meaning and reading, compared with radicals.
Once I get to vocab, I usually do 20 per day. I’ve found that a lot of the vocab tends to reinforce a reading I’ve already learned so I don’t have to remember as much and can handle a few more reviews.
I’ve found that this approach usually leads to a nice ebb and flow for each level where I tend to have more reviews at the beginning and end of each level when I’m reinforcing vocab and readings from a previous level or the end of the current level. But I get less reviews in the middle of the level when I’m usually learning the most new material and am the most likely to need a little more time breathing room to remember everything. I also feel like I rarely go through a long stretch without new lessons using this approach.
I like to apply the ‘clean as you go’ philosophy to WaniKani, as I do with most other things in my life. Basically clear out all the new things that come up the next morning before I have to go to work. If I didn’t do this, the number would pile up like dishes in a sink and I’ll never want to touch them again.
Barring the first levels, I’ve been keeping an average 7 day schedule since the start. As soon as radicals unlock, I bang them out in one sitting. If I’m able, I’ll go through the first wave of kanji then as well. If not, I’ll wait a few hours/until the next morning to get through all the kanji. Vocabulary gets done over the next 2 days or so, in batches of 15, 20, 30, or more… It all depends on what I can manage. I just make sure I’m at 0/0 whenever it’s time to unlock new things. I often look ahead at what will show up in the next lesson batch…not to deeply study it, but it does help to have a quick read through before they show up.
I keep this schedule not because I have something to prove…it’s more like extreme anxiety about falling off the horse crabigator. WK has been the thing that really got me motivated to study Japanese after trying and making abysmal progress for too long. The schedule it gives me is both a challenge and structure.
I find this highly relatable. It’s an inspiration to see you’ve been able to maintain that through 29 levels.
Yay, I’m glad it’s relatable! The structure and gamification aspects help so much with keeping me focused and motivated. WK is crazy amounts of work no matter what the speed, but I feel like if I let myself slip into a slower pace, I’ll lose my motivation. So, I’m keeping this up for as long as I can. It hasn’t failed me yet or made me feel burned out.
What works for one person won’t work for the next, but for me a combined rule of keeping the Apprentice queue around 100 items and doing no more than 30 lessons a day (usually; I’ve broken both rules occasionally) has allowed for a slow but steady pace without burnout.
I try to bring my reviews down to 0 once a day, but if I’m at 115 items in the Apprentice queue and I have 20 lessons still sitting there? Those will wait until it gets down to sub-100 again. There’s really no risk of letting things pile up this way, since it’s such a clear “if, then” for me. This is all less about fear of not remembering new items and more about how long daily reviews take if your Apprentice queue gets too full.
If I make an exception to the “around 100 items rule,” it’s usually to finish off a batch of new kanji lessons, since they’re what determine level progress.
When I started Wanikani I was so excited I was actually able to learn Kanji in a fun way I did everything as soon as it appeared. Then I tried to read something and I realized I have no idea how to read, even if I know some Kanji.
So I decided to read about it here and everyone said I need other things plus Kanji to understand Japanese, duh!
So now I do 20 elements a day, no matter what and grammar or vocab, depending on the day.
So it’s something like 20 lessons on WaniKani and then the others. But sometimes I feel so excited to learn new Kanji I just eat up all the lessons, heh.
But really, there is no right way to do the lessons. The way your brain feels comfortable ,that’s the right way for you.
Just experiment with what makes you happy and proud of you for learning and don’t let it become a chore. Stop with the number of lessons when it starts to feel like a chore and not fun anymore.
I prefer to go by brute force, that is I gobble down all the new lessons as soon as I level up. I takes me about an hour, because I skip all the sample sentences and only focus on radicals and Kanji.
For vocabulary, I just give a quick look to the words, and then I don’t care if I get them wrong 100 times during the reviews. Doing so drastically reduces the items I have to focus on, but also allows me to get a glimpse on the words (most of them are quite easy to remember tbh)
For me the real learning-time comes during the reviews: there I take time to explore the words’ meaning, look for fitting (or easier to rememeber) synonyms, consolidate the most difficult ones, etc.
I just start doing lessons and stop when I’m feeling bored/annoyed/irritated or in general feel like stopping. The only exception is right after leveling up, I do all the radical and kanji lessons for the new level immediately, to have them in the reviews and have them available as soon as possible, to speed up the leveling process.
I do lessons at 5pm (radical batch, kanji batch or 20-30 vocab) then reviews at 6am and 9pm everyday usually. Though I’ve just got myself of the review hell I got myself in when I was ill so haven’t leveled up in a while. It feels good to be back to my daily routine though 
I use lesson filter to get radicals and Kanji out of the way first then I do about 40 lessons in batches of ten with atleast 4 hours between each batch and the last batch no later than 9:30 pm. That way I can get all the vocab lessons done before I level up at the end of the week.