I don't show, so they don't really need to be bathed. But in the summer, I'll give them baths every few weeks when I'm bored on a weekend and they're looking extra dirty. Otherwise just a good grooming and sometimes just hosing them off when they're sweaty.
I used to hose down my horse during the summer after hot rides otherwise I don't normally bath them. It's honestly to much work and they end up rolling right after wards so they either have to be 1)either really filthy or 2)going out to a show.
My guys get done monthly sometimes more during summer. They get heaps of hose offs in summer but I don't always use soap/shampoo as that's what strips the natural coat oils if you do it too much. I generally only properly wash them if its before a show or they are really dirty or muddy. Im particularly funny about my horses looking looked after rather than left for ages without a bath like many of the other horses around. I hate seeing the other horses around who don't get bathed, brushed, protected from flies etc drives me nuts. I like my horses to be clean and comfortable. I can't imagine it being overly comfortable having bunches of dirt piling up underneath your hair...yukky :)
Lol that would drive me around the twist :P its probably a curse but I MUST clean everything that is dirty lol if they enjoy a roll in the mud, which jarred does, that's fine but he must pay for it either with a super grooming followed with a damp towel or a full bath depending on the thickness and stubborness of the mud :) if he chooses to roll again when we leave that's fine too but ill have to clean him again the next day lol