The discussion around what processes are applicable in what domain is complex and convoluted. This is painfully obvious in the #NoEstimates discussion where domain and context are many times missing.
One place to start is to develop a taxonomy of project and business types. The presentation below is my attempt to do that, using the paradigm I know best - flying machines. I've been in Page 11 and page 25.
With the notion of governance as a starting point, here's some guideance on applyibng governance once the project moves beyond the solo or small self-contained team