It depends on the horse, the level, are we in season or off season.
For my UL horse, maybe xc school 1 X a month during season. If not in season, maybe 2-3 x but mainly at training height, just to get him out of the arena/ used to galloping/ jumping. Or I’ll do 1-2 big schools before an FEI, but at this level,
I don’t school a ton of xc, and rarely in the off season.
For my young horse that is competing modified, 2 times a month during season. Less than if competing heavily. Pre- season, 1 time/ week only because he is gearing up for a level move up. And this all depends on if we have something to work on ( introducing new questions, seeing a different jump) or if he needs to see water or a ditch more… but this is highly fluid as if everything is going great, I don’t typical school xc a lot and when I do it’s never huge or long xc schools, keep it light and fun and accomplish what my goal is for the ride.
For a young horse with no experience, probably 2-3 times a month, depending on what horse needs, this could be as simple as trotting over a ditch for the “xc school” or walking/ trotting/ cantering through water. Or jumping logs for the day. I never do a ton again, I have a goal and stick to it and keep it fun. If I am teaching them what galloping & jumping means, I may have a friend ride a more experienced horse in front of me and we play “ follow the leader” as a game for the younger horse to learn to run and jump. So far, my younger horses seem to love that, and take to cross country well.