[jerf]

You don't. Having isolated code bases for each developer and a well-defined merge procedure is a feature, not a bug.

I've seen teams develop on a single target system, all of them bashing on the same source code base at once. It sort of works with a well-tuned team, that communicates well, and is capable of dealing with the resulting inconveniences, up to maybe 3 or 4 developers. Probably helps to have dynamic scripting languages in use by most of the devs so you aren't trying to time your compiles with each other's actions. And they still stepped on each other more than I would have been able to tolerate. There's no way this scales.

For non-code documents, by all means share. English prose doesn't crash if you start editing page 5 while someone else has an incomplete sentence fragment they're in the process of changing on page 2. But trying to edit code that way doesn't scale for squat.

From this point of view, whether it's "files" or "a database" or whatever that's being developed on isn't relevant. The point is that I actively do not want somebody else's half done work randomly getting integrated with what I'm working on right now.