I’m quite sure every state golf association has a slow play policy that is easily enforced at local events. It’s not complicated.
I'm mostly retired from officiating, but the Texas Golf Association and the USGA have specific pace-of-play guideline which if enforced, can alleviate some of the slow play problems. Both organizations seek to minimize the interaction between officials and players, with some "officials-in-charge" only allow intervention when a violation is already committed while fewer others encouraging moving slow players along (e.g. if there is a big gap early in the tee sheet, inform the players to stay in touch with the group in front of them even if they are "on pace". Me, my belief is that officials are there to facilitate fair play and anything I can do to minimize the need to penalize a player should be considered.
A big problem is setting the amount of time to play each hole and the entire round. Playing in groups of three normally, 4:45-4:50 for a round is typical, and better administered events often get done on time with minimal warnings and hardly-ever penalties for slow play. Me, 4:00 should be more than enough for most qualifiers, but it would risk the unpleasantness of rulings and penalties.
Juniors are bad; college golfers are worst. All organizations know slow-play is a problem, but rocking the boat creates headaches. The amount of player/caddie interaction is appalling. I worked a US Women's Am qualifier one year where players wouldn't even putt from 2' without the caddie reading and lining the putt.
I don't know that slow play is killing the game, but it sure has had an effect on my willingness to spend 12 hours on a course watching aspiring golfers trudge along. The shot clock is fine with me, though I wouldn't want responsibility for enforcement.