> You should know one abstraction layer deeper. More generally, I'd say that it's a matter of what improves your ability to perform the work you want to perfor

> You should know one abstraction layer deeper. More generally, I'd say that it's a matter of what improves your ability to perform the work you want to perform weighed against the possibly diminishing returns of investing time and energy in understanding things in more and more detail. Depending on the circumstances of your work, this may favor digging into more than a couple of abstraction layers (for example, an embedded developer that knows both software, digital circuit design and electricity can be immensely useful) or it may favor unquestioningly accepting the layer of abstraction you target as the whole truth (for example if I'm working on expressing some performance insensitive business glue logic for some proprietary platform, in which case I don't even have a choice).