I do my saddle and headstall maybe 1-2 times a year. But I keep my saddle inside in the house so it is not in extreme weather (hot/cold, mostly extreme heat here). But I do clean my cinch more often. Normally I give it a good cleaning after they are done shedding out for the spring, and then a good cleaning a couple times during the summer since they sweat so much. Saddle pads get cleaned about once a year, since I ride with a special pad under my thick saddle pads to help keep it dry, and keep the horse cooler. I wash my each horses bit maybe twice a year with a 3:1 ratio of water/bleach. After every ride I always spray off their support boots and bell boots, so they are clean for the next time. Brushes and grooming supllies are done twice a year and are soaked (betadine solution) and then washed (betadine scrub). Blankets and sheets are washed at the end of each season unless they have to be done for some reason during the time they are being used.

Hope this is helpful.