Probably very little - usually you need to know either if things are equal, or more or less than the last thing you measured. Or maybe you need to test if it is damaged after an unfortunate sequence of events.  Normally a fault that means my amp is bigger than your amp is not a realistic failure mode.

If you have another amp meter of any kind you can put them in the same circuit side by side and see how much they differ. A bit of last digit fruit machining on any digital device is quite normal. If it is your only meter, then maybe cal becomes more important, but otherwise just sanity check it against another known good from time to time.

Probably very little - usually you need to know either if things are equal, or more or less than the last thing you measured. Or maybe you need to test if it is damaged after an unfortunate sequence of events.  Normally a fault that means my amp is bigger than your amp is not a realistic failure mode.

If you have another amp meter of any kind you can put them in the same circuit side by side and see how much they differ. A bit of last digit fruit machining on any digital device is quite normal. If it is your only meter, then maybe cal becomes more important, but otherwise just sanity check it against another known good from time to time.