I’m right about at your level (I’m on the verge of moving into L6), so perhaps it helps to have a slightly different perspective. I’ve been keeping a journal of my studies, so I decided to take a look back and right as I got to level 5 I wrote:
This unlocked L5, which opened up 61 new items. Got through them all, but definitely do not feel comfortable with them.
Definitely was feeling your pain, in which I was like “how could I possibly remember all of this at the same time”. But not two days later…
Evening reviews were 89% accurate of a whopping 105 items to review. Nailed it, though, with all of the L5 items being answered correctly. I can’t believe how quickly I’m retaining these new items.
I think the most important thing to remember is that this is a long term thing. The goal here is not “get to L60”. The goal is to retain the knowledge, and if you miss some along the way and it takes a little time to level up, oh well. I’ve started to understand why some of the content is introduced together and it really seems well-structured towards “this is a good way to learn”. So just be confident in yourself and go for it. You might be surprised at how much you can remember.