I have a separate set-up for movies with a cheap sub that works just fine. I never touch it.
But, I am an occasional tweaker of my REL t9/x sub in the main system. First, it depends on what speakers I am using at the moment. If the Snell Type D are in play then the sub gets turned very low. If it's the LRS or VA Bach Grands then the level goes up a bit. Second, some recordings just need an extra bass oomph or reduction. Third, I have two listening positions - my main sweet spot and a little further back and higher where I work at my drafting table. The sweet spot is pretty neutral with tight full bass but the work spot has a bass bump which can be a bit annoying with some recordings. So yeah, I'm a sub tweaker.
I've been considering another REL to help even things out a bit. But now I am seriously thinking of adding an SVS with app to take care of the adjusting while just leaving the REL on simmer.