Well I would agree but I don’t want to click on WK every hour, guess I go find the right thang for myself.
The way my reviews are spaced out is quite convenient for me, my first batch is usually around 11am, when I am wide awake, and then from 12pm, I get maybe one batch every hour or two until 7pm.
Basically the way I do it is I do my lessons at 8pm each night, I am not sure what else I did to have them space out they way they have but in the end, I’d say just try to keep a consistent rhythm.
Usually in the morning, after breakfast! I’ve noticed that it’s the moment when my memory is more fresh and I make less mistakes 
Doing reviews multiple times a day (typically when I wake up, during a lunch break, when I get home, and before I go to bed) has so far helped me maintain a 600+ day streak. Missing even 2~3 review sessions in a row would still leave less than a full day’s-worth of reviews waiting for me 
I am the complete opposite! I am the most productive first thing in the morning, and just before bed =P
I do get my reviews done throughout the day, every hour if possible. But I get the biggest batch done in the morning, and the most productive review speed late in the evening.
i do my reviews about noon and midnight, with lessons at noon and first review at 4pm.
i’d generally suggest two main review sessions, 12 hours apart. lessons in one of those sessions, and a small review session (mostly just the first review of the lessons from earlier) 4 hours after the lessons.
then just fit that around your work and sleep schedule ^^
Anytime when you don’t have other stuff to do and you’re not mentally exhausted - that’s a good time to do reviews.
I prefer as often as possible (I use a mobile app) because I’m less likely to get frustrated doing small sets of reviews than letting 100 of them pile up. It also minimizes time spent early morning and late at night.
Just follow the 12h schedule and 6am and 3am reviews won’t be a problem.
Just in case you haven’t, I’d recommend reading Chapter 4 of my Guide for WK:
What I have found easiest for me is setting three times a day when I will do reviews.
I always do reviews at 6 or 7 am, 2pm (this is almost always only the lessons I study in the morning) and the last batch at 10pm. It helps me stay consistent.
Combined with the number of lessons I do per day, I don’t think I’ve ever had more than 70 reviews in a session assuming I didn’t miss a prior review session, which sometimes happens cause life happens. I average between 30-50 items for the morning and night sessions and 10-20 items for the 2pm one.
It isn’t the fastest or most efficient, but it is something that I’ve been able to stick to for the past 3 1/2 months without feeling burnt out or overwhelmed.
I just let them pile up and take care of them each morning, before I do anything else. As long as they get done regularly I know I’m making progress. If I have extra time I might do some throughout the day as well.
Going the max speed is overrated. WaniKani is tough enough without feeling obligated to go as fast as possible.
I do the largest pile of reviews before I get out of bed. My alarm will ring, I’ll pick up my phone all bleary eyed and brows the forum for maybe 10 minutes, then I’ll do reviews for 30-40 minutes before getting up showering and preparing breakfast. I’ll do 20 lessons (when available) after my first cup of coffee, and after that I won’t touch wanikani until after four pm when I’ll start doing a few reviews as they become available.
The most important thing is to stick to a routine.
I do my reviews for about 30 mins in the morning while getting ready to work, and at night before going to sleep.
My Process:
I wake up at 6 AM anyway. I have a dog; he needs to take care of business and can’t do it on his own (as in, he’s locked in my house bwahahahahaha).
That said, I generally do something along these lines:
Between 6 - 8 AM do the first set of reviews.
If I have Lessons, I will do 10-25 of them between 8 AM-9AM so that the first stages of SRS can be completed before I go to bed. If it hits 10 AM, I don’t do new lessons.
If I have done new lessons, I will come back in 2 hours from when I learned them and do them with BishBashOnce to learn them more reliably before Apprentice 2 level up.
11 AM - 1 PM do the next set of reviews. All of them.
5 PM - 7 PM do the next set of reviews.
After 7 PM I will check in one more time before 10 PM and close out all new Reviews so I go to bed, every night, with ZERO reviews to do. My brain needs this though some people don’t have this problem.
Next morning, get up and do it all again.
Now.
As is clear from the responses, I don’t think there is any one-size-fits-all answer.
It depends on whether you want to get through as quickly as possible, or, like me, you want to learn the material as well as you can and let the SRS do its magic. I think the former is easiest with multiple shorter sessions each day. The latter only requires daily (or at least almost daily) reviews and however many lessons you feel you can handle.
It sounds like you prefer a single daily review session. I’d suggest taking a look at your regular schedule and find three potential times when you’re unlikely to be interrupted: say, immediately after you wake up before life starts intruding, just before or just after lunch, and just before bed. Spend ten days forcing yourself to only do your reviews then. After a month, I think it will be clear which you prefer.
I prefer mornings with my coffee. My brain just seems to function best in the morning. I struggle whenever I do my reviews in the evenings.
As soon as they’re ready! 
The more you’re awake, the more tired your brain is. So the closer to the time you wake up, the better.
I do them pretty much soon after I wake up. If I’m not fully awake by the time I drag myself onto my computer, I check the forums then start the reviews.
When I started out I used to do them whenever they were available, but after a while I found myself actually getting too distracted by WK, checking it constantly so that I wouldn’t miss those reviews (irregular SRS of the first few levels + some items I didn’t get right getting pushed back making for quite erratic review times).
Now I just do them twice a day for old materials - after I wake up and before I go to bed - and follow the ‘route’ for new materials (for example, 8-12-20-19-18, twice a week, with varying batch sizes). It might not be optimal, but I find that having an established routine helps a lot (which is possible partly because of the current situation, which allows me to have this relatively stable routine, WK or otherwise).
But the best answer is probably what works best for you. 