by build-types you mean release to test vs. build for my own work? All my code gets released off a build server, and I'd consider it bad practice for a developer to be releasing their own code from their own workspace ...

Same build, sure, but you don't release it - you just run it on your own computer, as opposed to the development build you might ordinarily run, to make sure you didn't break anything.

I still can't help but feel this could be obviated by a more top-down approach, like decomposing into modules.

Even with a well-specified dependency tree there are areas where an incremental build can still bite you in the ass. Things like inlining and transitive dependencies ... I think you still need to build from scratch to be sure.