For me the Arduino is either for learning or prototyping, because of quick iteration time. For learning a new technique (say a new protocol or a new IC like a s

For me the Arduino is either for learning or prototyping, because of quick iteration time. For learning a new technique (say a new protocol or a new IC like a shift register) I'll do everything on proto board until I understand it. For prototyping I'll do the same and eventually switch to a custom PCB.