We’re roughly at the same stage I think, so from a fellow working-on-level-three’er, here’s what I’m thinking
I generally hold off from learning more new things until I can answer the reviews I get relatively quickly and effortlessly. When I’m asked for a kanji or vocabulary and really need to search around in my brain, I regard that as a good indication of my brain not being ready yet.
This can be annoying at times. You see new lessons and your brain thinks “yay, more goodies!” But personally I would rather see my speed go up with the items already in my review queue, than see my amount of kanji pile up - the latter only adds to my stress levels if I’m not comfortable enough with the ones I’m supposed to remember.
To me, learning all of the 2k+ kanji isn’t something I need to do quickly so I’ve accepted the fact that it will just take a lot of time. I mean sure, I’d love to know them all straight away and impress everyone and all of that but then I think, by going too quickly I’m only going to think badly about my brain, which is not even realistic because all our brains are fantastic amazing instruments. And all they need is time and context. And they perform poorly under stress and don’t like it when they are being underappreciated. So, in that sense - who am I really fooling but myself?
As long as I still need an age to recall that ‘small’ is ‘小さい’ (kaniwani), and that ‘内’ is ‘inside’ is ‘ナイ’ (which is mnemonically difficult), I’ve decided to just hold off.