[marcosdumay]

As you optimize a process to get 100% resource utilization, response time for any change gets closer and closer to infinity. You need some slack for things to work, and the more things change, the more slack it requires.

And that's not even considering how humans are physically unable to work 8 hours day in and day out.

[alexhutcheson]

There's even a whole book about this: https://www.amazon.com/dp/B004SOVC2Y (by one of the authors of Peopleware[1], which is also excellent).

[1] https://www.amazon.com/Peopleware-Productive-Projects-Tom-De...