Ask HN: Longer term Math Academy feedback

I'm in the process of re-learning a lot of maths, with a goal to move to ML research in ~2 years, and after discovering Math Academy (on HN of course) I jumped right into it.

It is great, but after a month of ~1-2 hours / day, I feel like it's a bit shallow sometimes, and given the amount of time I can invest, I may be better off going with the right books.

Would appreciate feedback of other long term / intensive users on that.