What in tarnation. For 100 bucks/month you can get 1-1 mastery learning sessions from math PhDs/postdocs that need money (like me! I am the postdoc!).
If you want to learn some math and are willing to fork over $50 a month, my advice is to find a competent tutor online*, tell them what your goals are, and work with them to produce an evolving, customized mini-course.
Have them pick material suitable for your goals, work through it in-session together so they can spot gaps in your knowledge/technique and make progressive problem sets to cover those gaps, and so on.
*A local tutor would be better, but I presume they will be prohibitively expensive in the average HN user's location.
The problem is that finding a postdoc that is also a good _teacher_ is a monumental task of its own.
Compared to an online platform that's being used by a ton of people, has lots of reviews and recommendations and that is, presumably, actively optimized through a feedback loop, it's an easy choice between the two. Also, a platform removes the friction of cancelling the engagement if the need to do so arises for whatever reason.
I mean, if someone I know points at a postdoc and says "this guy is excellent", then their recommendation will prevail. But chances of that happening are next to zero.
I have no experience with those platforms, so I don't know how deep the instruction is. After taking, say, a Calculus course there, would you be comfortable doing Spivak's exercises? If yes, that seems great.
No, you can't do anything in 1h/week, 3 hours should be the minimum, 4 is ideal, depending on the level of the class (I would ask for more than 100 for 4 hours a week if I am to teach advanced harmonic analysis, for example).
If you want to learn some math and are willing to fork over $50 a month, my advice is to find a competent tutor online*, tell them what your goals are, and work with them to produce an evolving, customized mini-course.
Have them pick material suitable for your goals, work through it in-session together so they can spot gaps in your knowledge/technique and make progressive problem sets to cover those gaps, and so on.
*A local tutor would be better, but I presume they will be prohibitively expensive in the average HN user's location.