Why would you be switching back and forth between stances?
I do because they tell me that when in an actual lethal encounter one may not have the luxury of getting cozy in his/her favorite stance. You might have to deal with the problem with your feet where they are.
Take any stance and swing as far left as you can go with gun extended without moving feet. That's Weaver (for right handed shooter).
Now swing to the right as far as you can---you'll have to turn your torso as you keep your feet in place and you'll be in Isosceles, or close to it. Only when your target is in front of you will you get to choose your favorite position.
That may work out for you most of the time, but not always.
I also practice one handed shooting. That's the only way you're going to get on a target back at 4 o'clock without moving your feet. Also the only way you'll get on a target to your right as you move left.
Most of my shooting is with a somewhat modified Weaver at targets to the relative front, but that's my comfort zone.