Btw i think keeping the lead shoulder in isn't a bad swing thought.
Eventually it needs to turn but the more the upper body is delayed the faster you can turn. What is bad is opening the lead shoulder well before footplant. If you keep the front shoulder in and open the hips you create a lot of stretch so the front shoulder can turn faster.
I wouldn't use the cue with everyone as there are guys who don't turn the upper body well but with some it can help. I won't tell them to keep it in all the way though, just delay the turn.
Eventually it needs to turn but the more the upper body is delayed the faster you can turn. What is bad is opening the lead shoulder well before footplant. If you keep the front shoulder in and open the hips you create a lot of stretch so the front shoulder can turn faster.
I wouldn't use the cue with everyone as there are guys who don't turn the upper body well but with some it can help. I won't tell them to keep it in all the way though, just delay the turn.