Self-study is the (wonderful) user script, I think you’re referring to the WK provided “extra study” feature on the dashboard.
Either way, I strongly concur: though I’ve never had more than about 350 reviews to tackle, the counter-intuitive approach to improving recall accuracy and working through a backlog is more review iterations of lower-stage items and less effort per item!
Apologies for the long reply, but I’ve strong opinions.
Understandably, most of us get so bummed out staring at a large pile of reviews that we don’t want to even consider doing any more reviews than necessary. So we bear down and try super hard to recall every item correctly, invariably going slower and getting worse accuracy. This is exactly the wrong approach in my opinion. At the very least it’s disheartening. For certain, progress will be slow.
Resign yourself to spending a little more time on WK per day than usual. Since you were gone for a week, expect it to least a week or so to recover. You don’t need to kill yourself though, 20% more time than usual should suffice.
Your reviews pile contains items in many different SRS stages. The stuff in stages 1 and 2 will be rescheduled for the same day (4 or 8 hours later) even if you answer them correctly: you really want to focus on these in order to make progress through your backlog. This is true whether they are from brand new lessons or items that fell back down from higher stages.
In other words, tems in your “reviews” pile break down into two categories:
Reviews for stuff in stage 4 and higher (guru’d items). I consider these retention tests more than “reviews” (as does WK itself: guruing items also unlocks lessons). You want to push yourself with these: try your best to recall the item (don’t give up until, say, 30s have elapsed).
Reviews for stuff in stages 1 and 2 (apprentice 1 and apprentice 2). These are basically the same as lessons: you are still trying to get these items to stick. You cannot “review” items in these stages too often! You should review these items repetitively, over and over, until you are 100% certain you can answer them correctly today (not necessarily days/weeks/months into the future). Go quickly with these: if you don’t recall it instantly, you need more iterations.
The remaining stuff in stages 3 and 4 is in transition between the two categories. If you answer them correctly they move up into retention tests. Wrong answers indicate more iterations are required.
Unfortunately, the WK UI doesn’t visually distinguish early-stage items from later stage items during your reviews (though there are scripts that will). Further, formal reviews forces you to wait hours to review any item again. That’s why they introduced the extra study feature (so you can get in extra reviews without waiting for the next scheduled review).
How to perform out-of-band reviews
The WK SRS won’t let you finish a session until you answer all items in the session correctly, but a big backlog means you either resign yourself to marathon sessions or (more likely) you quit for the day with several items (including stage 1-2 items) outstanding. Worse, whether you answer right or wrong you won’t be able to formally review an item again for at least a few hours.
So you must resort to informal, out-of-band, “free” reviews to get more iterations of early-stage items. There are two ways to accomplish this: extra study, or scripts (the self-study script in particular).
I prefer the script approach, but either will help:
Default Wanikani (Extra Study)
Extra study of either the “recent lessons” or the “recent mistakes” sections will help, but you really want to get through all of the items in either pile in one sitting. Multiple iterations through all of them would even be better. Even though extra study won’t let you finish the session until you’ve answered each item correctly, you ideally want repeated iterations until you’re certain you’ll remember 100% of the items every time (today).
I’d normally suggest using “recent lessons” first. Early in a level, you’re unlikely to have more than 60 or so items in this bucket. It shouldn’t take more than 5-10 minutes to review all of them.
In your case, you may not have many at all since (hopefully) you have stopped doing lessons for a while.
If you’ve more than 120 or so items in “recent mistakes” then you’ll either need to resign yourself to fewer 10-20 minute iterations, or (better, in my opinion) install the self-study script.
The self-study script is better in my opinion, for two reasons:
It lets you exclusively review stage 1-2 items. You can also shorten the workload further when it makes sense, focusing only on kanji/radicals only for example, rather than radicals+kanji+vocabulary.
It lets you “re-quiz” just the items you answered incorrectly the prior iteration.
Unlike formal reviews, self-study doesn’t force you to answer every item’s reading and meaning correctly to finish a session. Instead, it keeps track of the items you miss and provides a button to just re-quiz those items (alternately, you can also reset and go through all of them again).
This makes multiple iterations particularly efficient. Each iteration will have fewer and fewer items to review (you’ll gradually eliminate items as you answer correctly).
Once I’ve got the gradually decreasing number of items available to re-quiz down to zero, I try to reset and do one final pass through everything to make sure I’ve really got them 100% down. Often as not, I still need more iterations.
You’ll need to install the self-study quiz userscript.
You can also optionally install a launcher. My Ganbarometer script automatically launches it with just stage 1-2 items, for example (and is easily configured to include/exclude radicals, kanji, or vocabulary).
Get in as many reviews of stage 1-2 items as possible. Don’t worry about the rest: either you already know them and you won’t see them again for a long while, or they’ll eventually become stage 1-2 items.