For anyone interested in or associated with the project/mentorship side of this, watch this presentation from the most recent linux.conf.au: https://www.youtube.com/watch?v=ydS4vXNzN0I
Summary: if you think of this purely in terms of getting contributions to your FOSS project, and in particular if you think about the amount of time spent mentoring versus the amount of time needed for a developer to write the code themselves, you're doing it wrong. It exists primarily to provide mentorship so that we'll have more FOSS developers in the future, and from that perspective it works awesomely, whether or not any individual project gets lucky and gets a pile of useful code.
Summary: if you think of this purely in terms of getting contributions to your FOSS project, and in particular if you think about the amount of time spent mentoring versus the amount of time needed for a developer to write the code themselves, you're doing it wrong. It exists primarily to provide mentorship so that we'll have more FOSS developers in the future, and from that perspective it works awesomely, whether or not any individual project gets lucky and gets a pile of useful code.