chain stretched...............

[andrew_s]

But why on earth would you want your shifting performance and reliability to decrease like that??

I am also sceptical that you can extend a chains service life by 5 times simply by running it into the ground.

Your 1000 mile service life isn't determined by whether it's working OK, but by whether you can put a new chain on the old cassette. Chains that have worn enough that you can't still shift perfectly well.