Yes state of car battery, and its size too, are the main factors, after that if you plan on using parking mode a lot come the problem of you also have to drive some daily to recharge what you have lost while parked.
I changed battery ( small car / small battery ) in my 2012 car last summer, it was seemingly okay but i had some problems with a camera, and putting in a new battery also fixed those camera problems.
But i only use parking mode for 1 hour after i park, that cover all my shopping, and at home i have CCTV from my 2 floor apartment on my parked car so no need to run parking guard there.
If i was to feel unsafe parking in a place, i can just up the timer in the camera to give me the coverage i feel i need, but in day to day use i have the 1 hour timer to go east on my little battery.
If you park at home in your driveway or garage, you should not use parking guard, as nothing would probably happen there, or you should consider a CCTV camera or two.
Most / all cameras allow you to manually override the automatic change to parking guard, often by long pressing the power button after the system have changed to parking mode and so turn the camera off.