i use one for my low back, mid lower traps, sometimes my IT band, definitely my glutes. for your rotators, I would actually use a tennis ball, a foam roller is too broad.
you gotta rolls the sides. if you have trouble getting down when you first start squatting (beginning of your workout) roll out your glutes, you'll drop right into the groove. hmm....that sounds weird...
i use one for my low back, mid lower traps, sometimes my IT band, definitely my glutes. for your rotators, I would actually use a tennis ball, a foam roller is too broad.
If you aren't reaching new trigger points in your glutes, I recommend trying a denser deep-tissue massage roller (or even a lacrosse ball) - I use a 31" Regular Density RumbleRoller 90% of the time, and I also have a 12" Extra Firm RumbleRoller on hand specifically for my glutes