J Pull them to one side if they missed a throw have a coach Throw fifty balls to them. Miss a Grounder, roll Fifty Grounders at them, Are we building track stars or ball players ?.
I agree 50 grounders would be more beneficial, but RUN A LAP is quicker. I use it pretty sparingly and only for the whole team after a particularly bad defensive performance. Last Saturday after we made a few bad errors but eeked out a victory over a so-so team, I told them there was running to be done, and after they gave me some angry looks, I told them I was going to do the running because I made some pretty poor decisions coaching third base. They enjoyed it greatly as I ran to the fence and back.