"if you can't do it right, don't do it at all" or some variation of that
like, in most situations, no?? obviously there are some exceptions, but isn't it better to get bad sleep than no sleep at all? do one of your two loads of laundry? show up late to something important rather than completely skip it?
if you can't do something with enough effort to be worth it, then don't. i think that's a better saying, but it doesn't have a good ring to it. the original always made me feel like i had to be absolutely perfect as a kid, which did a lot more harm than good.