I am wondering… which is the less resource demanding way of use automations? One automation for device, or several devices in one? By example… detecting presence with PIR sensors and door sensors… is better create an automation for every device to controls it’s triggering and action, or create an automation called “presence detention” and add all devices and actions related? I think this will be more clear, but what about hardware resources? more?l ess? the same?
I would approach the problem from a different angle. Which one is more scalable and manageable from your perspective? Do not early optimize, home assistant is already handling many optimization things internally.
Worry more about what alternative makes it easier for you, than “resources” which are negligible.