I had a KMC 8-speed chain fail a "go/no-go" gauge test at 700 miles. It was the original chain on a hybrid comfort bike. I cleaned and lubed this chain every week, at about 60 to 70 miles weekly. I'm a skinny 62 year-old and hardly put a lot stress on the drivetrain. I chalked it up to poor quality. I get at least 2 to 3 thousand miles on SRAM chains before they fail the stretch test. I vote for poor quality of the original chain and unless you get a repeat performance on another name-brand chain, assume it's not you, it's the chain.