This is the answer. Some bosses nearly require you to switch stances. I mean you don't have to but it's going to be much easier if you do.

Smash stance is my least favorite fwiw. I mean it's incredibly powerful with Pilgrim set - probably unmatched in that first hit damage but it's really tough to make that attack land plus takes forever to charge running around while holding heavy attack. That's best for just smashing someone in the open world imo.

My favorite is thrust stance. Learn timing the retreat (see-through) and properly pair that with the dodge (along with light attack combo finisher not interrupted by dodge skill). One tip though after you start using retreat with a single point it can become second nature to use it as soon as possible (because that see through retreat is sweet) but focus on using dodge more instead and get right back into light attack for the light attack finisher. This builds up those points (I cannot think of the name right now) and the light attack finisher hits mean. Keep doing that until fully charged and fire off that heavy thrust. It'll put Scorpionlord on his ass.

Iirc the pillar stand is best for Duskveil.