I think you're on to something – you read for different reasons; sometimes it's to know where to intervene to fix a bug or add a feature, sometimes it's to know

I think you're on to something – you read for different reasons; sometimes it's to know where to intervene to fix a bug or add a feature, sometimes it's to know how a really specific algorithm works, sometimes it's to find the event loop or procedure that sequences a high-level process. One of my first "a-ha, so that's how it all works!" moments in coding was when I found the main loop in a decompiled codebase for of Minecraft.