At the risk of being sacrilegious, I’d personally re-order that entry in the knowledge guide:
- Do your reviews.
- Do them every day, without fail. Probably even on Christmas.
- Consider doing at least a few of your available lessons. Maybe even all of them on when you can, but not too many at once or you’ll pay for it over coming weeks and months.
Amen!! I live by this wording. 
However: Note that if, like me, you only do reviews once per day (not multiple times per day) you’ll miss the 4 and 8-hour schedules.*
I used to think this only mattered if you wanted to go as fast as possible (absolutely NOT my personal goal). But it also directly impacts your cognitive load and SRS efficiency.
Basically, the job of an SRS is to give you frequent, repeated reviews of hard stuff, and less frequent reviews for things you find easy. Normally, new stuff in the earliest stages is always hard: it takes several repeats before it “sticks”. Without those 4-hour and 8-hour reviews, you’re making your daily reviews harder.
This is getting off topic, but I think the key to keeping Wanikani from becoming overwhelming boils down to just a few things:
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Try to keep the SRS stage distribution of upcoming assignments fairly balanced. Especially avoid too many early-stage items (“Apprentice” and “Guru” items, or stages 1-6). A common heuristic is to keep Apprentice + Guru/10 under about 150 or so. [Self-promotion: my GanbarOmeter userscript makes this especially easy to manage.]
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Also try to keep the timing distribution (scheduling) of upcoming assignments balanced. It’s far better to have 100 reviews scheduled each day for a week than 700 scheduled on the same day. This is where the accelerator analogy comes in: doing lessons (or a backlog of missed reviews) in a few huge batches rather than spreading them out is invariably a bad idea. Slow and steady is the ticket to keeping the stress within reason. [The ultimate timeline userscript configured to show the next 120 days of assignments by SRS stage can help you visualize how well you’ve spread out your upcoming assignments.]
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Review “new” items (items in stages 1 and 2) repeatedly and frequently, every chance you get. I find it extremely beneficial to get “extra” reviews in for stuff in the first two stages, outside of the Wanikani schedules (mainly because I don’t do multiple review sessions per day). [Again, the GanbarOmeter makes this trivial by launching a self-study quiz for just these items.]
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Try not to worry too much about your current level, level-up time, when you’ll “finish,” leeches, or especially wrong answers! The only way the WK SRS knows if you find something difficult is if you answer incorrectly. Anyone beyond level 3 is literally paying for a service to quiz you more often on stuff you find hard to remember: answering incorrectly is how you take advantage of that service.
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That said, sometimes you’ll realize that you keep seeing an item as it keeps bouncing back down from higher levels. You’ll occasionally need to figure out why this keeps happening. For me, most often it just means I need more repetitions (i.e. “don’t worry about leeches and let the SRS do its magic”). Other times I’m confusing it with another character and I need to figure out which character that is and figure out some trick to keep them straight.
I think #4 is particularly important. It’s human nature to want to answer everything correctly and progress quickly, but it’s honestly better to relax about incorrect answers: they’re actually the most important part of the process!
* It takes 4 hours from completing a lesson before it’s scheduled in stage 1. It takes another 4 hours and a correct answer to move it to stage 2, and yet another correct answer and 8 hours to move it to stage 3. That’s a minimum of sixteen hours to move an unlocked item to stage 3.