RE: 2 Questions
On the first question...if you are talking about a 5x5 routine where you are using the same weight for all 5 sets and getting to near failure...then YES,
4-5 weeks using this method would be a good time to take a week off.
On the other hand, if you using a progressive weight scheme stretched over a 10-12 week period you would be fine. This is a typical approach
for powerlifters in my 16 months experience. I made a 50 lb gain on deads, about the same on squats and about 25 pounds on my bench
in a 14 week cycle. I took a few days off about week 12 , cause I was getting fatigued, but the plan worked great IMO.