Hi @[email protected]
The calibration frequency depends on your requirements.
You can do it monthly, yearly, biannually or never, or before any critical project...
For school or hobby use where high accuracy is not important, you can leave with the factory calibration.
A important source of error is the temperature drift, which causes mostly offset error, of about 40ppm/*C.
To prevent/minimize such, leave the device for 10-30 minutes to heat up before starting the measurements.
This is also