Haha, my usecase is really simple. I have a couple of applications that need to run at the same time on the development machines and they only need to be updated once or twice a year. With subtrees, only the one person who maintains the subtrees actually needs to care about the other applications, and the other developers can mostly ignore that the other applications exist.
If we used containers, a Docker compose file would make things even simpler for us, but alas.
I recently started using git subtree[0] instead of dealing with all the problems with git submodules, and have been very happy with the experience so far. It does copy every file into your repository, though.
If we used containers, a Docker compose file would make things even simpler for us, but alas.