From H00se Neckts: What does the term "milking" meAn?
All successful "Milked" games end at the latest possible year, which is 2050AD. The reason for milking the game and not winning the game as soon as possible is because the end-of-game-bonus is less than the score you will receive by:
1. Controlling the maximum number of tiles without triggering a Domination Victory (See MapStat utility.)
2. Creating as many Happy/Content/Specialist citizens in your cities.
You can also receive points by discovering Future Techs BUT the number of points you get is, in practice, not worth the trouble!
This may seem very self-evident: One has to be careful, while milking, not to trigger a Domination Victory OR a Cultural Victory...........otherwise you obviously won't make it to 2050AD!........thus terminating prematurely The Milk Run!
Milking has become most significant in Game Of The Month (GOTM) and High Score Hall Of Fame (HOF) competition......HOWEVER, for GOTM, Aeson et al have developed a scoring system that provides for a higher End-Of-Game Bonus thus providing more incentive for players to Win the game at the earliest opportunity and not keep the game going (viz. "Milk") until 2050AD.
My understanding is that the Aeson Scoring System is not effect for the HOF competition, thus Milking will remain the way to get the highest scores for Standard, Large & Huge maps. However, Small maps have recently been accepted for submission to HOF and it's quite possible that a "Fast Finish" could generate a higher score than Milking to 2050AD!
Incidentally, to see your current score, click on the "H" character on the bottom right corner of the main map screen. The "H" may not appear for the first few rounds of the game.