I routinely adjust knees, feet shoulders etc..and for many reasons but most importantly is to keep them moving and functioning properly.
There are indicators that would lead me to check specifics but we are reacting to problems at that point and I like to be preventative. I also clear out misalignment up the spine first so brain & body are talking before I branch out to alt-parts. If central nerve system is stressed or overloaded, helping its periphery is pointless in my opinion. For example, if shoulder has decreased range of motion, asymmetry, inflammation, reduced joint motion/play, tenderness etc.. I want to make sure the nerves branching from spine that control shoulder function aren’t being aggravated or irritated. This would go for wrists, knees, or even feet.
We need to always make sure are nerves are functioning properly because everything is servant to the nerve. Nerves influence all function in the body which is why as a Chiropractor I look there first. If your nerve system was in your feet, I would be looking there first but it’s in the spine so that’s are center piece.