I think you should go at whatever pace feels comfortable for you.
My pace is very fast and it took a while to get the hang of it, but I can describe the other extreme to you want to know what it’s like…
Disclaimer: my method might not be the best for learning, but it’s just the way I do things. It’s probably worthy of criticism. I’m trying to speedrun – this method definitely isn’t for everyone.
On the day of my level up, I immediately do all of the radicals. Past level 14, this is easy, because there’s usually 8 or less, and a majority of them are characters you’ve already seen.
I then do all of the kanji lessons in one sitting. I spend maybe 3-5 minutes on each character. I close my eyes and spend several minutes experiencing the mnemonic. My mind usually takes me to a memory from my childhood or formative years – this memory becomes the “setting” for the mnemonic. In effect, I’m attaching a “fake” memory (the mnemonic) to a real memory. It’s mentally exhausting and requires intense concentration, but eventually I reach a point where I can feel that I won’t forget the mnemonic.
One hour later, I’ll do self-study on all of my apprentice kanji to make sure I really didn’t forget them.
2-3 hours after that, it’s time for my Apprentice II reviews.
The most I’ve ever done in one sitting was 31 kanji (on level 15). I managed to pass all of the reviews without any mistakes. The lessons themselves took under 2 hours.
In between the Apprentice I and Apprentice II kanji reviews, I’ll go through the list of newly unlocked vocab and knock out all of the “easy” ones – e.g. the ones with intuitive meaning based on the characters, ones with a straightforward reading (usually jukugo with no weird readings or rendaku), kana words, or words that I happen to already know. My goal is simple: I want to have ALL of my vocab lessons done before I guru the new kanji and even newer vocab becomes unlocked. I do the easy ones first and save the hard ones for the next 3 days because I’ve already overwhelmed my brain with all the new kanji.
3.5 days in, all of my lessons are completed and I guru the radicals/kanji and start on the next set of kanji and vocab. There’s less kanji this time, so that’s easier (and the night/day before, I’ll look them over just to have some sense of what I’m in for), but there’s a TON of vocab that gets unlocked. My new goal: finish all of the vocab before I guru the new kanji and level up. Again, I pick the “easy” ones on the first day and save the “hard” ones for the following days. By the end of the week, all lessons are finished and I’m ready to guru the last remaining kanji.
I guru the remaining kanji and level up. Past level 14 or so, it’s not bad because I’m only guru’ing like 5 kanji or something, so not THAT much vocab gets unlocked.
The downside to this method is that you learn the kunyomi for the characters late. My kanji/onyomi reading retention is insanely good, but I tend to get hazy when it comes to kunyomi readings – I don’t spend as much mental energy on the mnemonics, and I also I don’t think the WK vocab mnemonics are as good as the kanji mnemonics. e.g. it took me forever to remember the batshit insanity of the 予め mnemonic – “a raw (nic) cage”. I must’ve failed that review a half dozen times in a row.
Because my lessons come in large “bursts”, sometimes I’ll have days with a “light” amount of reviews in the in-between hours. If I have little to do, I use Self-Study tool + Item Inspector to preemptively do all of my reviews for the coming week. One day I spent a few hours doing 650+ self-study reviews just to keep everything fresh in my mind.
Sometimes if I’m bored (e.g. on a long plane flight), I’ll self-study review all of the 500-something kanji I’ve learned just to see how good my retention is. I usually do this on smouldering durtles in anki mode so it’s quicker.
Other days, I’ll spend time doing self-study on all of my apprentice items to keep them fresh.
Because wanikani has the weird “rounding down” thing, I try to aim for 6 days, 21 hours on each level, but I fail to reach it most of the time.
This method is not for everyone and it risks burnout because it becomes all-consuming. I faltered on some levels, but I’ve mostly been able to manage it so far.