> Over all there was no scientific proof that testing and best practices lead to better results than just making spaghetti without a recipe.

Which best practices? I can’t see how a team without certain practices could be that effective. Eg, version control, having good backups, a good communication culture, code review, config management to prevent “it works in my machine” problems, and many other things.

For code review specifically, I read a paper years ago claiming a dramatic decrease in defect counts in companies who practice this