When my life really was hell I used to play maybe up to 10 hours a day but now I probably only play 2-3. I think there's probably a part of a guitarist's technical development where practice leads most efficiently to improvement, I think I might have passed that level now so trying harder produces less reward. This is one reason why I don't practice so hard. That said I still can't read much music and my playing centres around a few scales, there are still big gaps in my playing and if I got the motivation going I'd like to stuff em.