I've used climbing gaffs before as a Trainee Line Mechanic.
But all they are used for these days, over here, is as a test for new Trainees.
The Insulated Cherry picker and the use of Pole ladders has more or less ruled out the use of gaffs, as has the wider use of concrete poles for LV/HV lines.
Our pole ladders have a length of chain at the head, covered with hose,between the stiles, which also aids sliding the head end up the pole, when extending it.
Yes, learning to use a set of gaffs, takes a lot of practice, it's a matter of getting your arms and legs co-ordinated and also sinking the gaff spike into the pole surface at the right angle, slip and man does it hurt, it also ruins your confidence to a certain extent too!.
Especially when you are less than half way up the pole.