I've used it while at Purdue, and while I was an instructor in Michigan, at PTK and YIP. Basically I use it for a take-off roll, rotation, and low-altitude abort on the long runways. This was of course in SEL's like PA28's, C152's and C172's, no twins.

In fact, as an instructor, I would split the radio's if able(or I would isolate the student and they had no idea), and let the ground-controller know what my intentions were, and if they could pass it on to the tower controller. They would give the "option" clearance to verify what I had requested, and the student was none the wiser.