For live tree pruning, I do a small cut at the bottom first - maybe quarter to half an inch deep. Then cut from the top down.
I don't know chainsaw safety well, so this might be wrong. but I saw someone do it once and it seems okay when the chain saw is on the pole. I do the first cut with the tip of the blade if I can't get in there properly.
I don't know why it pinches without that first cut. I blame physics for being stupid.
Thinking on it some more, the tradition in the family is to do the small branch pruning first, then once all that's done with hand pruners or pole pruner, get the saw. I just sort of kept the tradition. But now I'm wondering if it's to make using the saw easier?
I don't know. I feel like I'm really bad at pruning as they always complain I take off too much. I just do my best and each year, cut it back a bit more.