[rossy]

> anything I install from source sits in /usr/local

To be fair, this is the norm on Linux too. I have never used BSD as a desktop operating system, but everything I've installed from source also sits in /usr/local. It's the default install directory for most Linux build scripts and I feel dirty if I add anything directly to /usr that the package manager isn't aware of.

[derefr]

Right; the distinction isn't so much "installed from source" as "installed without the package-manager's knowledge." If you `apt-get source`a Debian package, apply a few patches, and `debuild` it, the resulting package should install to the /usr prefix like the rest—because it's being tracked like the rest.