Dan Slimmon:

Ideas are funny things. It can take hours or days or months of noodling on a concept before you’re even able to start putting your thoughts into a shape that others will understand. And by then, you’ve explored the contours of the problem space enough that the end result of your noodling doesn’t seem interesting anymore: it seems obvious.

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But as you get into more senior-type engineering roles, your most valuable contributions start to take the form not of concrete labor, but of conceptual labor. You’re able to draw on a rich mental library of abstractions, synthesizing and analyzing concepts in a way that only someone with your experience can do.