We are talking about different things. By "specialty" in this thread I think is meant a specific course of instruction, with a certification at the end.Yes. It’s called coaching.
If something is worth doing, it has a value. Paying an expert for a few hours can be exceedingly effective.
Coaching, seminars, clinics.....these are all ways for an instructor to help someone, but there is no certification attached.
I gave an "intro to deco" seminar recently to some folks who wanted to know what their computer would do if they exceeded NDL, and how they should respond. They each used two computers, one set on Nitrox -- which is what they were diving -- and one set on air. They let the air computer go into deco for a few minutes, and then did what it said to do. They never actually exceeded their NDL for the gas they were breathing.