If I feel any lag in intensity then i take a week off to get motivated again, and to refrsh my body.
Never sacrifice intensity, no one ever got bigger or stronger by going through the motions. Changing weight is different though, take what you can normally do for 4-6 take a way 20 % and try for 12-15
example squat 300lbs for 6 now would be 240lbs for 12