I don't normally have control over my switching and sometimes I rolladex ( switch often and very fast ) a lot. But it does get easier. I've had to learn to go with the follow and not get myself upset about it. If I get upset I switch and that leads to a snowball of switching.

To make switching easier in T I would have something comforting with me at T's. A stuffie or pillow. My T has learned over time what triggers certain pieces ( alters ). He knows certain things to say that will trigger. But it took him a few years to find what my triggers are and to be able to trigger without hurting.