By far, the highest most used and abused game room machines out there would be the old Chicago coin big ball bowlers. These things are tanks.
I know some that have been on route for 50 plus years getting played hard every night and still going.
There is no counter on these but if you run the numbers many of these would be well over 1 million plays and still going strong.
United bowlers would never last this long with the butterfly pin mechanism. But the CC games are rock solid games