Worked in projection booths for ten years; never once heard them called that.
Of course, I worked mostly in multiplexes with platter film-handling systems –no changeover required.
In the older places I got to make a few of them myself with a weird little cutting tool designed for the task.
And no, I never spliced in any cocks –at 24fps, it’s a little more noticeable than they’d have you believe.
I did once get the pleasure of splicing together a colleague’s treasure-trove of about twenty or so ’70s porno trailers into a feature-length epic and played it for friends late one weekend. Funniest ninety minutes of my life.