One of the equipment items that I think every shooter needs is a Shot Timer. There are lot of variations on this and which route you go I don't really care, but everyone serious about shooting needs one. This is why, to measure skill. If skill cannot be measured, how do we know if it is good or bad?
Once we have the ability to measure skill, we then also have the ability to measure the improvement or decline of skill. Once we can measure either of those two, we can evaluate the effectiveness and efficiency of our practice and make adjustments where needed.