Some manual film cameras could still take a photo using certain settings even if the battery was dead. I had a Minolta with that ability. Try that with a digital camera!
I have gone months with dead batteries in my F2 (the camera at least) because I don't use the camera's meter except in an emergency or if i need a quick exposure. Same for the Nikkormat FT3. And my Hasselblad 500CM does not even have a meter and all the Compur shutters are in the lenses themselves. My F4 is a total brick without batteries and because I do not use autofocus or autoexposure, the batteries in my D700 and battery pack can last for well over a month easily before needing recharged. Plus I alternate my batteries in the D700. When the battery in the battery pack needs recharged, I remove it, and move the one from the camera into the battery pack and then replace the one in the camera with the freshly recharged one from the battery pack. That way each battery is recharged the same number of times as the other one.