I only ever found it necessary to "grind" once or twice at level caps, but I also did side quests on my way. If you're actually doing everything as it's presented, and maybe do your daily dungeon roulette, you should keep up just fine.

The only time I really had to break off the MSQ to grind anything was when I first hit 60 and didn't have enough item level for the Final Steps of Faith, since I got there during the Heavensward patches and they hadn't started handing out catch-up gear from quests yet (and Normal/Alliance roulettes didn't exist yet, so catching up on Alexander and Mhach was a pain).