Process heaviness is not a goal. The secret is to be as close to the minimally viable as is safe.

Undocumented code and decisions are just a more slowly accumulating cost, it is no less costly than bad or failing code.

This is a reason I love having outspoken and extroverted devs. The guys who love to talk so much that they will explain in extreme detail and at length.

I was reading through an old bug yesterday, and the guy who had done some work in that area had left a 5 paragraph explanation of what had gone wrong, what he thought may have caused it and some things he was planning on doing. Having that written down was invaluable when I got to the thing a year later.

Process rigour is not the goal. Communicating what is strange and different is. If you have guys who do that naturally, great. If not, you need some process.