if i have a bad day because of forcing things, putting on too much size, etc. i take the next day off.
if i have several days which cumulatively add up to the stuff above, i take the next day off.
i generally get those 2 days of head-clearing with the weekend, so i don't like taking monday off. however, i've learned to be extra patient - if i get antsy, i can get myself in a bigger hole.
so after a bad week, i try to use the weekend to clear my head. but during the week, i might take a day off or something