A big part of the speed boom is that pros are realizing swinging at 95% speed actually goes just as straight if not straighter than 85% speed regardless of the technology. I think it has to do with generally a bigger turn in the backswing, and also the intent of trying to swing fast makes me swing more efficiently and for me personally my release of the club is way better. It also simplifies what you’re thinking. Instead of positions, I’m just thinking speed I think most amateurs can gain a lot from speed training. It’s super simple, just hit 20 balls swinging as fast as possible with some sort of speed monitor (after a solid warm up of course) and see where it takes you