How do you decide between a monolithic repository and polyrepos for internal tools?

Hey everyone, I'm really curious how teams set up their code for internal tools. Right now, we put everything in one big repo, all our services and shared code. It's super handy for managing dependencies and making sure everyone uses the same tools. But, as our team gets bigger and we add more stuff, builds are taking longer. And if something breaks, it can impact a lot. I've heard some people argue for separate repos, saying it makes CI/CD faster and shows who owns what more clearly. So, what do you think about when you're deciding this, especially for tools that really depend on each other or share a lot of parts? Does a monorepo ever stop being worth the trouble, even for just internal projects? I'd love to hear your stories, good or bad, with either way of doing things.