As often as I can, since I need to condition for show and CDE. Unfortunately with Washington weather that may be only once a month in the winter! I'm also limited on where I can drive so don't get out nearly as often as I would if I lived near great trails, quiet farm roads or had an indoor arena. Still, my goal would be three or four times a week per horse (I have two) if I had the weather and the time.
When we're stuck in the barn for seven months out of the year I go back and work on any foundation skills they're weak on, teach them new things like halter or showmanship, and do a LOT of trick work. Winter is our time to build up the things that take patience or lots of long slow incremental work and get them solid. Come spring we're ready to switch gears and go back into driving, refreshed and better educated.
Leia