MainzMan:
...It may make decent money from hole in one challenges but for normal play I can't see how it can be a big earner. I think most people agree WGT make most money from ball sales and since putts don't wear your ball out an 18 hole round should only cost most players 18 shots off their ball...
Incorrect. Mulligans do cost shots on the ball even when putting. That was discussed when mulligans were implemented.
That makes the par 3 course the best one for putting practice. Only one shot to reach the green, putt using mulligans for practice for the max (I think it was raised to 15 shots per hole max?). Next hole - only one shot to green. Putt to the max again. Repeat for the round and you've taken very few full shots but a lot of putts that count as wear and tear on the ball.
EDIT: Mainz - This is from the FAQs
"Is there a cost to use a mulligan?
If you use a mulligan during a Practice game, the ball you are using will be degraded by two hits instead of one hit. Mulligan putts will also degrade your ball by two hits."