Dexcom 6 doesn't need to be calibrated anymore. Well, it still needs the first calibration when you insert it, but none other than that. Lasts for some 2-3 weeks before sensor needs replacing.
The Dexcom G6 system does not require any calibration, insertion is remarkably pain-free, and it lasts for 10 days. I've had it for a few months (after a couple of years of using the G5 system) and I can't imagine living without it.