I’m going to challenge you buy saying this. I’ve progressed much much quicker by studying the differences between. は and が, because I learn it and I forget it. I don’t think about it when using it anymore, however it’s in there somewhere when I get lost.

Same for English. I did learn it, I also forgot it. It’s not in there but it is. Same for being able to explain verb conjugations.

I agree though on some points for sure. Especially how well my German fiends (for example) understand the theory of English compared to me.