> When you are in a major Chinese city you may street sweepers sitting on the side walk chitchatting. The first thing you may think of it as waste that could be eliminated. But it also acts as a buffer.
TL;DR: Pretty much what you said, but he labeled it "margin" instead of "slack". But yeah, you need some.
It's very hard to sell slack to management and so in "well run organizations" it ends up trending towards zero. And then everyone is surprised at the resulting catastrophes.
I use this extensively when planning activities with my children. It's a fun challenge because they're both too young to tell the time, much less read, which are constraints one does not normally encounter in their work life.
I think "slack" is a much more general concept than efficiency vs latency. The slack itself allows low-latency response to emergencies but the activities that fill the slack time can be valuable in ways that often aren't legible to the org hierarchy.
It was something along the lines of "The optimal amount of slack in an organization is not zero", or something like that.
The argument was that, since it's impossible to plan for every eventuality, you need a certain amount of slack capacity in order to retain some flexibility. And that by always using 100% capacity, we end up dysfunctional.
I think the same is true for our personal lives.
But the endless treadmill of self-optimization, side-hustles and ever more commitments leaves us unable to cope.