And what's the largest you've worked with? You're talking like you've never worked someplace with multiple programmers. Or maybe you're used to places so large that you have multiple programmers on each active project.

In my experience it's common to have one programmer working on an ordering system, one working on an accounting system, one working on reporting, one working on customer service, etc etc etc. All of these at some point touch the same customer and order tables, but none of the projects intersect with each other enough that the programmers need to care about each other.

Do you really work someplace with multiple programmers, and they're all working on the same app?