I’m an AA, with onsite access to an indoor, who does did not show last summer but intends to show next summer (Third level)
My horse does best right now when I ride every other day, but both weekend days, so that works out to 4 times a week. We often do a groundwork day or a trail ride day or tool around bareback as an extra day. We’ll be doing more groundwork days in between rides as we get into heavy blanket season so that he has some time to move around while naked most days.
I think what is best depends on the horse. Some people are able to progress with 3 rides a week. Some people have very energetic horses that do best with 5 or 6 rides a week. I’ve experimented with fewer more intense rides and more frequent but lighter rides. My horse gets muscle sore fairly easily when worked too much, but also gets uncomfortable when not ridden enough because his natural posture is so crap.
If you’re just getting him back in shape, maybe try for 4-5 light and short rides per week (assuming he’s sound and not returning from injury that needs a special protocol) at first and do core strengthening exercises and some more PT exercises or stretching activities on the days you don’t ride (if you go to the barn every day anyway).