Monorepo or not?

We are currently brining XSLT & XML files to GIT. Basically everyone of them is a separate project, only in special cases more than one of them has to be adapted at once.

I know the general rule is to have one repo per project, but I wonder if this is also true for something simple like XSLT & XML files.

Some team members are hesitant and bring good arguments for a Monrepo in

• Handling of just one repo
• No need to create new ones / checkout every time you need to adapt something
• In case of the need to change multiple you can do so easily
• Overall less administrative overhead, you find everything in one folder on your laptop

What I can bring in as counter-arguments

• The overview of the repo-history gets useless with a monrepo, it's just too much going on
• I wonder if performance will get worse if GIT has to handle everything at once (there might be some binary files - e.g. ZIP as well)
• It might be good to have to sanely check out what you want to work on instead of having everything there- although this arugment lacks a bit, also today everything is one big folder (with subfolders), and we plan to utilize pull requests with reviews, so no harm should be done if someone makes a mistake
• Most threads tell you to do so

I am not convinced, and would appreciate some guidance.