garyt1957 gotta chime in here on the wider stance means less turn, that MAY be so. Also, understand that if you are too narrow, you can’t rotate around as far without throwing yourself out of balance, so you may be able to rotate further with a wider stance. I believe consistency could be improved from a wider stance with less leg movement, if that’s an issue you currently have, but it’s really about being comfortable enough to do it consistently.
The high shoulder concept might just be a mental picture for you to keep from dropping down too much, just a thought. I do see a lot of people trying to swing out to in by slinging the club around on a flat plane, generally drooping the shoulder on the back swing. Keeping it level from your start point as you rotate will hold plane better and force rotation instead of casting the club around yourself. Not sure what his actual point was.
I used to work with an instructor once or so a year when I couldn’t find it, the guy looked like he lived in the back of a van and was about 5'4" tall, swings nothing like me, could watch 2 swings and fix me, it was unreal. Find the right guy or gal and it’s amazing. He always said he would pay to have a swing like mine, to which I said I would pay for his handicap and we got along great.