True, battery powered zigbee devices do to extend battery life.
This is the case for most z-wave or wifi battery operated devices as well.
Still I was surprised my Sonoff buttons show the same behaviour: few times a press works right away, but often it needs to be pressed two times.
At the same time I have to be careful not to perform a “double press” 
These are the only zigbee devices (of 70 in total) showing this behaviour.
Sensors however should not show this behaviour; all my zigbee sensors respond right away → I guessume you possibly have to
- add more zigbee routers in the mix (almost any mains powered zigbee device acts as zigbee router)
- tune your zigbee & 2.4GHz wifi channels, because they can interfere badly;
- replace the power unit, which can improve wireless performance:
https://community.homey.app/t/advanced-zigbee-troubleshooting-on-homey/115930?u=peter_kawa
Battery operated 433MHz and IR devices don’t have this “delay” or “not responding immediately” issue, because they only send a signal as “fire and forget”; there’s no network or checks to run.
