No, because we know what the contact does. From the first time the voltage changes, we know the user pressed the key - provided we are happy that we don't have a noise problem.

And the contact bounce time is reasonably known too. Say 20 - 50ms, depending on switch type.

The point is that in certain apps it might be preferable to respond in 5, not 35ms. But noone can press and release a switch in 50ms!