It is hard to anticipate all the things that can go wrong. One example is consequences of inactivity. Some of them are more serious than others. Some can be reversed, others cannot. Here are a few things that come to mind.
Although some of these may seem to be of minor consequence, collectively they can add up and have a major impact. Not only can some of them be wasteful, they can also cause fires if left unattended for long periods of time. Just like changing batteries in fire and carbon monoxide detectors, it is a good idea to check around on a regular basis.
Surprising things can happen. My thermostat batteries failed prematurely. When it happened a second time, I realized that each time there had been an extended power outage. While the power was out, the thermostat had been futilely trying to turn on the furnace or air-conditioner. This is what drained the battery.
The same thing can happen if a battery is being charged when there is a power outage. Batteries can be ruined if they fully discharge. It is best to pull plugs and turn off circuits when there is a power failure. In any event, when power is restored, there can be excessive loads and power surges if loads are not added a little at a time. Motors require about three times as much current to start than they use to keep running.