Thank you! That's exactly what I was wondering. I figured they almost had to be "shake awake" or always on.I run a Holosun 507C-X2 and it's shake awake. Battery life is advertised at 50,000 hours (if using dot reticle)...plus it has solar backup. I plan to change battery annually. Battery is easily accessible from the side (no need to remove red dot from firearm for battery change).
Trijicon RMR Type 2 doesn't have shake awake and is always on. It has a slightly lower battery life (advertised), although should easily get you through a year of "always on". It does have a 16.5 hour battery conservation mode, where brightness is reverted back to auto level from manual. Optic must be removed from firearm to change battery.