I'm going to have to agree with your boss.
in reply to modular app development - where do your modules live?
Personally, the make, make install is just too slow for a rapid edit, run, edit cycle. It would make me 20% slower with no apparent gain.
There are a couple cycles you are looking at, the "developing individual CI module: edit->unit test->edit->unit test->..." cycle where, as pointed out above, you don't really have to "make, make install" every time.
The other is the "install multiple CI modules->integration test->find bug" where you are really testing the install process itself, so it really makes sense to do a full "make install".
If your whole app fits into one CI (configuration item), where no module is (or ever will be) useful without all the others (take a close look if this really is the case), then the vast majority of your development time can be spent between "make" and "make test", only rarely getting to "make install".