Students go to school about 12–15 hours per week. Other than that, it’s studying and writing papers. They make their own schedules, pretty much. Especially if one didn’t need certain courses for a degree, they could pick and choose what classes they wanted according to interest AND according to schedule.
Another option would be to audit classes, meaning to sit in on them without having to do the work and without receiving a grade.
If I had the money to continue the lifestyle I have now, so in other words all my bills were paid and I had spare cash comfortably to buy what I needed and travel when I wanted, and my only obligation was 12–15 hours per week to learn whatever I wanted, hell yes I would take that in a heartbeat.