Latency sneaks up on you

People are shocked by a corollary of this.

If there is a process with a large number of steps, and in the general disorder of life, work arrives at one step randomly, the desire of people to have 100% utilization at each step conflicts with the desire to produce any product at all.

That is, at 100% utilization, partially completed products would stack up in queues and throughput goes to zero.

60% utilization is a better goal, you can do better than that IF you take "random arrival" out of the situation.