There are ways to save battery without doing any of that. It’s just that I can’t be assed to roll my own.
Case in point: the BeCode AIR+ camlock on my locker at work: that thing achieves fantastic battery life with a single (admittedly large) button battery.
I actually got curious to know how it achieves this, and it’s really quite clever: apparently it seems to detect the patterns of times when I use it, and sends probe pulses more often around those times, and a lot fewer outside of them. I know that because I arrived at work really late once, and I had to wait quite some time for it to open - long enough to wonder if it was broken. That’s what prompted me to study it.
Also, it seems to detect when the locker room is lit and goes to deep sleep if it isn’t.