I've spent over 6 years working on 5+ legacy projects that had millions of lines of code and maintenance teams 30 times smaller than the army of contractors who

I've spent over 6 years working on 5+ legacy projects that had millions of lines of code and maintenance teams 30 times smaller than the army of contractors who developed them. And I've learned all the small nit-pick maintainability issues made no difference. Whether or not there was a style guidelines, and whether or not it was enforced made little difference. Things that really made a big difference were giant bone-headed architectural decisions like "just save persist this data as serialized text", "lets write all the business logic in stored procedures", "building the software on a terrible platform". And having some type of identifiable domain model helped a little too.