When I was training, for most of last year, I would train very hard for 3-5 weeks and take 5-7 days off. I wasn't using a lot of supps, but I continued using fish oil and casein protein. If you are bulking it will benefit you to keep calories up.
If the supplement is not directly related to the workout, it's fine to keep taking. On the other hand, it's always a good idea to take a one week break from any supplement other than perhaps protein powder (which is not necessary, only convenient), so there's no harm allowing the "breaks" to coincide.
PS, now I am trying for 8 weeks on, 1 "deload" week. We'll see how that works. I'm also going to rotate my program less frequently.