I really want to try MathAcademy.com. How quickly do you think someone doing light study could move from a Calc 1 -> advanced stuff using that site? In my case I could put in at least 30 minutes to an hour a day.

I can't speak to the advanced stuff but here's my stats on Fundamentals I:

Total time on site (gathered from a web extension): 40h 30m Total days since start: 32

Total XP earned: 1881

Since "1 XP is roughly equivalent to 1 minute of focused work", I "should have" only spent 31 hours. I did the placement test and started at ~30%, and now I'm at 76%. I'd say 75% is stuff I learned in HS but never had a great handle on, 25% I never knew before.

Overall, I'm quite happy with the course. I'm learning a lot every day and feel like I have stronger fundamentals than I did when I was in school. The spaced review is good but I do worry I'll lose it again, so I'm thinking of ways I can integrate this sort of math into my development projects. It's no Duolingo, you really do have to put in effort and aim for a certain number of Xp per day (I try for 60 XP rather than time).

Hard to say but this should give you an idea [0].

At that rate, less than a year is reasonable.

[0] https://www.justinmath.com/what-is-the-highest-sustainable-d...