When I was an apprentice in a small company, ...

I had the order to set up Subversion on our machine with a fresh installation of Linux Ubuntu. The order included to create only a single repository for all projects we were working on. He totally missed the point how version control works. In his opinion it is just a place to store backups, and nothing more.

In some setups make sense to have one repo

https://stackoverflow.com/questions...

In this case it didn't make any sense. The projects were deployed seperately and most of them had no connection to other projects. I've already told my former boss what a mess it would be, but he wouldn't listen to me. He've have been questioning my knowledge about version control systems. He didn't even know about version control systems a week before the conversation. The commits were conflicting because for example someone made small changes without telling anybody. His solution (which isn't great at all) was to store the local repository on a shared windows file system. The problem wasn't really solved at all. We were overriding each others changes. It was a complete mess.