To give u an example, I have a Japaneese delivered CONGO with no wear at all around the flippers, and the japaneese installed game counter with the original date on it shows 1800 games (set on 3 balls) from the original site Taito operator etc with a book inside the game showing servicing history etc to confirm all n sundry is legit with very low game count. (yes, the japs do really look after their sited stuff just like Home Use stuff which is why jap games are in such demand) So, I would imagine, a game with some wear showing would be as follows.

some wear -  8 thousand games.
mid wear - 14 to 20 thousand games
wood wear - 25 to 30 thousand games plus.

I judge a game by the condition of the mechanicals on a game. ie- pop bumpers n sling shot moving parts, flipper slap etc etc will always tell a games real usgae. Insert wear obviously tells a story, but cliffy wear areas arent really a great way either cause some ball pop up areas do attract wear easily like on a data east Last Action Hero where the ball always flys accross the gold ticket etc, and the 2 x square sink holes always get shot every game a million times.

Also, I have seen some games with no wear around the flippers at all, but they have been very very high usage. But yes, cabinet wear can tell a story, sometimes it doesnt matter cause the game can be still really looked after. Some people in Home use only games slap the living shit outta there games with their individual playing style, which I certainly dont.  When i see a person playing a brand new game who is a bad slapper, it makes me cringe. A pinball is like a nice lady, be gentle with finesse, they will last longer. lol