More importantly.......

What do you clean & lube with?? (Don't say gas, coffe can, toothbrush & 3 in 1 oil)

I got 3800km out of my 10 speed chain. I clean it with a dry rag and lube it every 250-300km and use Finishline's Dry Lube. YMMV, since I stay right next to the sea and do a fair bit of climbing.

I ride with a guy who is a bit OCD about cleaning his bike and chain. The chain and cassette are always sparkling like new. He got 15,000 miles on his last chain before it stretched enough to warrant replacing. He uses Easy Clean (white lightning).

I, on the other hand, use the same lube but don't clean so much and my chain is usually a little dirty. I get about 3,000 miles on a chain. I'd rather just buy chains more often than spend all that time cleaning.

I use pro-link gold and lube every 200-250 miles. Get about 3000-3500 miles per chain and about 7000 miles out of a cassette.
The chainrings seem to last at least twice that.

Chain wear. Isn't it mostly how much pressure you apply on the chain, short or long bursts, prolonged mis-matching of front to rear rings?

Two types of wear: the length and then the rollers. then the rollers in relation to the links.

Then there's the lubes: all petroleum based lubes have detergent added to it. That detergent looses its ability faster than we think.

So its a constant battle.

I bet it's more his riding style, rather than compulsive cleaning and lubing, that makes his chain last so long.

I met him once, and thanked him for writing the chain cleaning article.

This!
Ultegra chains are 20US$ at wiggle.