Work late doesn't mean efficient!

Now is 8.04pm and i am still in office.
We (colleagues & myself) jus complate our task and just waiting the boss to review the works...What a tired day!
I wonder, why we need to wait? Lots of time wasted in waiting & waiting, and not really spend the time on doing the work. I hate that resiously.
To me, that is really not efficient at all in spending long time in completing a task. Work late = Not efficient!!!
In fact, i am in rush to fatch my little daughter back..pity of her waiting mummy & papa pick her home...