Stumpin is the best form of practice for hunting. Every shot is an inknown distance, which will train your eye much better than regularly shooting known distances. You learn to find holes or lanes through brush and branches, and how you CAN make a shot through a seemingly impossible collection of obstructions.
Picking a small spot on a leaf,the top of a stump, a pine cone hanging from a branch reinforces target focus.
Even if you slightly miss the spot, by an inch or so, you know that you would easily be within the vitals of a game animal.
But you are shooting your bow, and it becomes an extension of you. You will find you think about the shot less, and it "happens" more naturally.
I think many of us are somewhat limited in the distance we can shoot at a target, or we tend to stick within the comfort zone. Stumpiin allows you to take many more shots at longer distances, which hones your skills, tightens your form and makes you a better archer.
Plus, its fun.