For my show horses, I lunge them in the round pen every other day. Adult horses, I work up to 20-25 minutes at a trot, split into about equal time in each direction. For yearlings, I round pen them working up to 15-20 minutes every other day.
All my show horses are out most of the time. I only really stall them the night before a show. Most of them play a lot which helps to keep them in shape. However, if I was being more disciplined, they would be stalled either every night or every day (basically in 1/2 the time) so they could wear the sweat wraps I bought years ago and don't use like I should

OH!
My show horses have a simple diet. Mine get a complete senior pellet and soft orchard grass hay. Leading up to and during show season, they get more pellets than hay. They also get ground flax seed 1x a day as a coat enhancer and have free access to minerals.