[@SpeakNoEvil] Great question! Usually, it's been observed to be a pretty quick flipping between white and black in the aftermath of a particular traumatic incident, but not always. (My character Echo's stars only half-changed, but are now lightening again, for example.) You totally can do a slower changing Star if you want! Just know that they might be under particular scrutiny from the doctors and headmaster because it is a rather nontypical response. If you're good with that, absolutely go right ahead! :D