I understand Wanikani uses an SRS system, so it lets you review certain items whenever it thinks the time’s right to do so. However, I would like to do my own reviews in between, like all the level 4 radicals or so once in a while.
How can I do that, i.e. reviewing items that I want to review when I feel the need to do so?
You can of course have a look at them manually here but there’s no way of reviewing other items like you’d do in a normal session.
That is only a problem in the very beginning, though, when Wanikani is still a bit slow. A few levels in it’s very unlikely you’ll feel the need to study ahead as the reviews and study items pile up.
Other than that you can always use downtimes to start studying grammar!
Yes, this is easily solved with user scrips thankfully. OP don’t worry too much about the SRS. If you wanna study more, you can with a few tweaks. But, it’s worth asking yourself why, you think think you need to do this extra studying?
After all, SRS is about reducing the amount of active time studying, allowing you to absorb a lot info with less time spent actively doing so. That is, consciously doing so.
As someone that is now doing my second run of WK, I think it’s worth saying that you’ll need to have reasonable expectations on yourself. You’re about to cram thousands of study-items, kanji, radical names and vocabulary, into your brain in a much shorter time than Japanese people spend in school doing so.
So, you will forget some stuff. That’s fine. It’s always easier to relearn something you’ve already learnt once. And it just means you didn’t get to actively use that information soon enough to make it stick.
Forgive yourself for all you will forget, and try to accept that it’s part of the process. And that you are still moving forward.