5 hours
5-Hour Rule: If you’re not spending 5 hours per week learning, you’re being irresponsible
Michael Simmons

I would say this is on the low end. I’ve heard as much as 80% of your “free” time should be devoted to doing something that improves your growth.

While that number is extreme, I’m close. I devote 100% of my commutes (about 14 hours per week) on audiobooks and podcasts. I listen in double time, so I get in easily 20–25 hours per week just during my commute.

Keep it simple. Pick the low hanging fruit to maximize growth, then you can pick at the margins later.