During show season I like to ride 6-7 days a week anywhere from 45 minutes to an hour and a half a day. If I am going to ride 7 days per week, one or two of those will be out on the hills walking.
During off season, when I'm in school, I try to get out 6 days a week and ride for 45-75 minutes. I don't have access to hills in the winter so he just gets at least one day off per week. I find he doesn't stay as fit in the winter, but I think that's inevitable.
He also get turned out for 6-8 hours a day, every day (minus like, christmas or if it is stupid amounts of cold/rain/wind he won't be out for that long, just long enough to clean the barn)
ETA: And when school is really bad I either will drink a lot of caffeine, not sleep and finish my work at night, or get someone to lunge him for me.