I dont think i'd be doing many precisions....
why not? it forces you to learn how to jump with correct form and to land properly.
if you don't pull your knees up, put some arc into your jump, and come down on the target rather than hitting it laterally, you will fall on your arse LOL. and when it's wet, you have to land on the balls of you feet for sure, or else you WILL slip.
doing precisions in the rain will reinforce the habit of ALWAYS jumping and landing with correct form and with perfection every time.