Long ago I changed the default commit message to include headers “Why?” and “How?” to remind myself that I need to explain why a change is made (what this article focuses on), and how it is made (different implementation approaches considered). I followed this format for a long time. I was in the top 1% for commit message length at the company.

To stay concise, I think bullet trees are the best. I've never had to make exceptions to this format.

Top level groups high-level concerns (optional). Below that (required) are short distillations of those concerns answering "why". Below that are descriptions of "what" was/wasn't done. A final optional level digs into deeper implementation detail.

The vast majority of my bullet trees are just those two required levels. Each commit message is rarely more than 10 or 15 lines long, and people really appreciate them. I appreciate them too since I'm the most likely to read them.