It depends on whether I have a competition coming up or not. If I'm competing, I will ride 6 days a week for 2 weeks leading up to it, and alternate how long I ride depending on how he's feeling under saddle. Some days I'll ride for up to 1 1/2 hours if I haven't been able to unlock a block in him, other days I'll ride for 20-30minutes when everything feels good.
I'd say on average per week, on Bob, I would spend maybe 6 hours in the saddle as well as in hand work and lunging.
Then riding other horses as well, hmmmm I guess at the moment I would be spending about 12 hours in the saddle/week.