I think almost half of that 10 hours would be rest. In concept art for example it's estimated that a newbie can have 6 productive hours in the day, whether drawing or taking in info. Once you get to pro level that 6 can go up to 8, which is still under 10. I've personnally found that to ring very true for myself, once I get over 6 hours of work per day I get very very slow.
I'd probably split my time between learning about techniques, practicing techniques, drawn studies of whatever I'm learning that day (anatomy, structure, spacial visualisation, colour theory, etc...) and probably a couple of hours exercise? Use those remaining 4 hours to rest my brain doing something not to do with geometry like sport or going on a walk, making sure I don't burn out. If I have some more energy on any given day, probably doodle something.