And consider that because every folder can have its own .git subfolder, we can have several paralle trunks/repositories at the same time, meaning we have a fore

And consider that because every folder can have its own .git subfolder, we can have several paralle trunks/repositories at the same time, meaning we have a forest. I haven't really seen specific guidelines as to when and why should anyone start a new repo. Are there some? Or is "mono-repo" the best solution, and when and for whom. Surely we need more than one git-repo in the whole world?!