You need to seal the surface to reduce weather wear. regardless of traction issues.
I agree you do not want to seal more often then needed. If you do not seal you will watch the top layer wash away have exposed rock or shell depending upon were you are located.
MMR Track grip builds rubber on the track, adds grip and side bite, does not wash off like sugar. Many tracks apply compound every week. We usually reapply every 4th or 5th race weekend. dependent only on reduced traction/laptimes.
Ft Myers ran some last race. They still have a bit too high of tire wear. Most likley from the sand in the sealer done last summer. Lap times were back were they needed to be.
One of the big gains is that if you do have a shower you are back racing on a good track sooner.