Goal today: swap the chain and cassette on my commuter before the weekend, because the drivetrain had been making a sound I can only describe as a bag of gravel rolling downhill.
I'd been measuring the chain with the Park CC-3.2 every few weeks. It had sat at the .75 mark for about a month — that's the point I try not to pass on a 10-speed Shimano system, since you risk pulling the cassette life down with it. I waited roughly two weeks too long, as it turned out.
Removed the chain with master link pliers. KMC link came apart cleanly first try, which is worth noting because it usually doesn't.