"[P]aired programming is about optimizing for the team" (source: http://goodrequirements.com/2013/pair-programming/). Long-lived feature branches optimize for the individual. A useful alternative is described at http://paulhammant.com/blog/branch_by_abstraction.html.

What is your definition of "small"? The projects I worked on at ThoughtWorks for over three years numbered in the dozens of developers, all pairing, and all committing directly to master.