I'll go first.
I used to think building systems meant more templates. More prompt libraries. More "frameworks" saved in a folder.
But after going through the Foundations and sitting with the idea that "the file system is the skill", I've flipped. Now I think the best system is the one you don't notice. Clean architecture, thoughtful naming, and a way of working that Claude can see without you explaining it every time.
The templates were a crutch. The thinking underneath was the real thing.
What about you? What's something you believed coming in that you've quietly changed your mind on?