On golf training aids

It's widely accepted among copywriters that the best one working in the golf industry is John Carleton. He writes for one particular client who brings out a lot of golf instructional materials. Maybe he's written for other clients also, since I know he's said he's written over 100 golf letters, yet his current client doesn't have that many products listed on his website. Or maybe they've retired a lot of products that stopped selling, though I'd think that John's copy could continue to sell any product that hasn't already been seen by golfers, and there must be new ones looking for golf training aids all the time, plus new teens and adults just taking up the game of golf.