IMO working on long running branches is asking for trouble. Specifically, it discourages refactoring, as it's impossible for any one developer to grasp how any change would affect his colleagues.

If everyone works in master, you try it, run the tests, and if they're green, you know it works for everybody. You don't risk breaking feature branch X that did a refactoring in a different direction in an overlapping area.

Of course, this implies that you adhere to a CD/CI philosophy. Code always compiles, all test always pass. If your process involves code being uncompilable, unintegrable or test breaking for substantial periods of time, you'll need branching.