Bravopilot Shotgun starts are typically a group start not playing their own ball. I expect they take longer to play.
Scramble takes longer just to pick up all the random balls
In general, no and no.
However, shotgun tourneys sometimes have 2 groups on the tee, on some, if not all, holes, especially charity ones, so those take forever to play.
Scrambles should not be slowed by having to pick up random balls.
It's usually because the majority of the golfers suck donkey balls, hence the format.
JMO from experience and various scientific Spuzzervations.
😉