you will have abstractions - black boxing, interface overviews etc, humans can only hold so much detail in current context memory, some say 7 items on average.
Of course, but even those blackoxes are not empty, they've got a vague picture inside them based on prior experience. I have been doing this for a while so most things are just various flavours of the same stuff, especially in enterprise software.
The important thing in this context is that I know it's all there, I don't have to grep the codebase to fill up my context, and my understanding of the holistic project does not change each time I am booted up.
