Are you having any symptoms of chain wear other than what the gauge is telling you?

I use a Park tool as a quick check and a ruler if near the end of life. I ride daily in all weather and generally get about 2500-3000 miles out of my cheap KMC chains. I re-lube when the chain starts to get noisy. Every few months, remove, clean, and re-lube. If I wore out a chain in 300 miles, I would be looking for another cause.