Ok...

[Slick]

800%!!! That's almost the same as total extermination. I typically use 300% or sometimes even like 260% - with a 5 year delay. I would think that anyone could win being at 300% of 2nd place after > 5 years. It's just a matter of how much you want to continue to develop your empire for your own edification.

Slick.

[AgentZero]

I usually set it at 400%. 200 if I'm looking for a quick game. Last time I set out to play a total extermination game, I was playing with in a galaxy that had about 100 systems. I got to the point where I had 31 systems and 3 other AIs had the rest. I'd built massive fortifications on all WPs leading to soon-to-be-enemy territory, mined them heavily and had thousands of satelites over all the WPs as well. My invasion fleets numbered 4800 (and I had about 60 pop transports racing around trying to fill up smaller colonies).
I then launched my massive invasion; 48 100-ship fleets (16 per enemy empire) burst into enemy space through artifically created WPs.
And ran smack into the stiffest resistance I have EVER seen the stock AI put up. I'm lucky I used my own WPs because the largest of the three had the main WP to my space defended by sixteen Starbases! And these weren't your mamby-pamby stock Starbases, either. Each of the behemoths clocked in at 6,000kT.
Anyhoo, I realized that I'd be looking at fighting tactical combat for every single planet if I was to be assured of victory. I then whipped out the calculator and plugged in a few numbers.

69 systems for me to conquer with around 10 planets each makes 690 planets. Call it 650 for arguments sake. 650 planets * 15 minutes average tactical combat = 9,750 minutes = 162.5hours = 6.7days non-stop playing, but since I only average about 2 hours a day game time that worked out at 81 days.

So, to conquer that galaxy would require the better part of three months just counting combat, and not taking into account repair & maintenance, replacing lost ships & troops, protecting conquered worlds, AND running the rest of my empire to boot. Needless to say, I declared a moral victory and went to bed. ;-)

[geoschmo]

I don't know if you guys are talking about solo play or PBW here, but I've been in PBW games where 300% or even 400% would have been too low. It's entirely possible for the 1st place player to be that much stronger then the 2nd place player and still get beat if the others gang up and play a good end game. Especially since score is so easy to manipulate by building lots of cheap, low-tech ships. And as bad as it is being in a game that seems to drag on for ever, it's much worse to have what is shaping up to be a really good ending to a game be aborted by an arbitrary limit.

[Alneyan]

I second that Geo. In TGE3, my score was above 300% of the second player for many turns, and I did not even play to have the highest score possible (that was just my usual Base Space Yard/Light Carrier production). It would have been very easy to create even more inflation, by building empty starbases, or something along these lines. But I was still a long way off from being able to take on the whole galaxy on my own, though a few Empires would have suffered in a global war.

I would much rather vote on ending the game, when it looks like an Empire cannot be defeated, no matter what. NGC3 ended a few turns before the final clash against the leading Empire (we would have been crushed, but still, it is much better to be defeated in the field than by numbers).