i dont take days off really, 3-4 times a year that i take week long vacations, those are pretty much the times i dont touch weight ( but usually do some cardio ). But once i feel i hit a platue, again i dont take days off, just much lighter weight ( probably cut the weight by 40%), and just do high volume, and fewer excercies. for example if i was doing 6 excercises for back totalling 24 sets, now i'd do maybe 3 exercise for 10-12 sets but lighter weight and higher reps. it not the TRUE definition of rest, but this works for me