I've been using a chain checker tool (similar to the one in the image below) to determine when I need to change my chain. Right now my tool is telling me the chain is at 50% life/wear.

Yet when I do a search online re: when to replace a change, I'm getting mileage/distance recommendations. Frequently in the 2,000 to 3,000mi range (https://www.bicycling.com/repair/a20...ur-bike-chain/). This seems kind of young/early to me.

So I'm torn. What's best practices? Replace the chain by distance or when the chain checker tool says the chain is at 75% life?