We are efficient and have no further improvements to make. - EQUALS -
We have no idea if we are efficient or not.
Only by continuously focussing on efficiency, constantly having improvements to make, making them, and then identifying the next improvement, could one say "we are efficient" with the added caveat "and this is what we are doing next to stay that way".
Alarms should sound when you hear "we are efficient and have no further improvements to make".