I guess in my mind I always thought that the wild horses at some point during the year would cross water deep enough that their "happy spot" would be washed by the water. This went for the mares too.
As far as the hooves go, the amount of travel with the wild horses would self trim their hooves.
Since we have forced our horses to live in a relatively small area compared to what they would if out in the wild, we need to look after certain needs. Trimming is one as well as a yearly cleaning of their sheaths and udders.
I don't get to fanatical about the sheath cleaning, and do it once a year. Fortunately my gelding is quite clean so it's pretty minimal. My mare gets her udders (more specifically the crease between them) cleaned more often just for comfort. They tend to collect a bit of dirt there.