Assuming that your horse has absolutely everything he needs (food, bedding, a warm stall, plenty of blankets, and a pasture mate he neither humps, maims nor gets abused by), what does your horse need to be the best version of himself?
When the assistant trainer was riding Tristan last summer, I told her that he is a horse who needs processing time. He functions best and happiest when he has a day in between intense rides. He is not a horse who needs or wants work seven days a week.
AT remarked that she’d often heard people say that about their horses and had never found it true, and then a few days later she came back to me and said “Wow, it’s true!” Giving Tristan a day completely to himself in between training rides resulted in a totally different horse: more forward, more willing, and he had clearly digested the mental lessons and come out better for it.
Granted, my current once-every-ten-days schedule is not ideal either! But Tris would do very well on a solid, consistent, 4-5 day a week schedule with two, mayyyyybe three, of those days as a hard drill. The others would be non-brain work: trot sets, hacking out, you name it.
It works well for me, since I’m not in a position in life (or quite frankly, a desiring frame of mind) to have a horse that NEEEEEDS that 7 days of work a week.