> The claim you should know everything about everything you work on is an intensely naive one.

It is true that you normally do not need to know everything, or even most of it.

Despite this, it is necessary to be able to discover and understand quickly anything about the project or system on which you work.

I have seen plenty of software teams that became stuck at some point because they could not solve some trivial problem that required a zoom into the project where some extra skills were required for understanding what they saw, like understanding a lower-level language, or assembly language or some less usual algorithms or networking protocols and so on.

Or otherwise they were stuck not because they lacked the skills to interpret what they saw, but because they used something that was a black box, like a proprietary library or a proprietary operating system, and it was impossible to determine what it really did instead of what it was expected to do, without being able to dive into its internals.

So I believe that the environment should always enable you to know everything about everything you work on, even if this should be only very seldom necessary.