Good point. My old iPad's battery is still lasting very long, but I don't know how it would behave if it were indefinitely plugged.
Air 3 I've got on ebay-like site holds pretty well but the same model that my partner got from official dealer had always issues with touch recognition.
My old iPad lasts weeks on its battery if I don't use it, I can only imagine it actually sleeps and would not answer network requests in this state.
Congrats for the successes :-)