mine always has been involuntarily and very fast. while i know some things that can trigger it (stress is a big factor), there are a lot of times also that there are no triggers i can figure out. well, i guess that's not completely true..though it can feel like it happens out of nowhere.

i don't always know reasons. sometimes it seems like a cycle that keeps going once it starts...like a switch gets flipped on and like a revolving door that exhausts me. it can take hours for the effects of dissociation to lessen for me, especially if it's been particularly severe. sometimes, i won't even know i have been dissociating until like a week later.

i have a lot of variations, reasons, etc. so i would guess it's like that for you too, things you cannot pinpoint.

i'd think if it was voluntary, you would be able to notice it more because it would be a choice to do it compared to involuntary where you don't have warning signs of it, don't expect it, and don't always know it's happening.