Paul Hammant? Thank you for your blogs and thanks for putting this site together, they're very informative. I work at a company that has been doing "Cascade" model for close to a decade [0], very similar to TBD but not quite the same. In addition to having a mainline trunk repo which everyone's work is pushed to, we have started utilizing Phabricator in the past few years -- it enables us to have short-running feature branches which aren't public to the upstream repository but can be shared if necessary and used for review (I'm not sure how similar this might be to GitHub flow? We use Mercurial).

[0] http://paulhammant.com/2013/12/04/what_is_your_branching_mod...