This matches my "ideal" way of writing software, which is something close to "reverse waterfall". Start with the non-negotiable truths at the lowest level, then work your way up towards the goal, which is sufficiently defined. As you go, the patterns became apparent, collapsing into nice abstractions.

The code always ends up nice and clean and modular. And, since I'm working towards the idea, I can say "here are the modular pieces I have to work with, dictated the fundamentals beneath, how do I use them to accomplish the task?". When working from the idea, I think it's easier to want to write something to achieve the immediate task, in a "not see the forest for the trees" kind of way (abstractions are about the goal, rather than the reality under). Of course, both directions are required, but I get the best "separation of concerns" going in reverse.