Yes, it's fine to do that for battery maintenance when they aren't currently being used.
Some people like to keep their batteries ready to fly at any time, so they get into the habit of fully charging the same ones every couple of days without...
They have a pretty darn good history of being accurate. That's the first example of an error on a significant issue that I've heard of. That one example is no reason not to rely on the manuals.
It's always mentioned in DJI's manuals. So whenever you buy a new DJI product, it's a good idea to download the manual from their website and get familiar with all the details about your new device.