I wonder if people could explain more broadly how to know if footing is "good" or not. I ride at a place with a sand indoor, and recently a small outdoor ring was installed, also with sand. However, no one uses it because word on the street is that it is "too deep" and could put unnecessary strain on the horses' legs. To my uneducated eye, it doesn't seem any different from what's in the indoor, and we have this beautiful outdoor going unused in the pleasant fall weather. What is the rule of thumb for what's ok to ride in, and what sort of feel would help you tell apart good vs. bad?