I don't use the neckstrap.
I used to use it, but it had a tendency to "put the radio on", and then lean over, and almost stick the antenna in the prop.
I instruct once in awhile, and I use the pass the transmitter method (that's a whole 'nother discussion).
I also use a lot of body english when I fly, in fact, I couldn't stay inside of a 10'X10' area. A neckstrap is in the way.

Jetts