I think that's right, but organizationally challenging to implement. In my experience engineers don't really think through this question carefully, and have to

I think that's right, but organizationally challenging to implement. In my experience engineers don't really think through this question carefully, and have to be prodded to do the right thing, or at least the thing that better serves others or their future selves. There's also a hump to get over until network effects take over, where engineers have strong incentives to participate in the monorepo. In your iOS vs web team example, we might imagine that they eventually want to run an integration test against the same API, whose team helpfully provides a hermetic version of the service for testing against. (Dropbox wrote some bazel rules for this sort of thing: https://www.youtube.com/watch?v=muvU1DYrY0w https://www.youtube.com/watch?v=muvU1DYrY0w)