Probably as soon as you don't know why an object appears in your tree. I'm not at all an expert on Di as the only project I worked on that used it a lot, I was also responsible for refactoring it such that spring di was only optional by annotated constructors, because spring startup is atrocious and we wanted to use part of the application in lambda.

I've not used it since because the project I inherited suffered extremely from nih syndrome.