In general I strive for as much decoupling as absolutely possible. Now this does not mean things are not connected, it only means that they are not hardwired. This is where polymorphism is so great. Now I suspect your description is not of an OO design, but consider it from an OO perspective for a second:

If Module A used a type-of D, and Module B used a type-of A and a type-of C and Module C used a type-of A and a type-of D, etc etc etc.

The big idea here being that you never hardwire D to A, but just make A expect an instance of something which looks like a D, and acts like a D, but does not have to actually be D.

However, very often "what you should do" (decoupling) and "what you need to do" (interconnectiveness) collide. It just takes experience to know when you actually over-engineering something, and when its good design.

Well thats my 2 cents, now its bedtime.