CO washing does not use shampoo at all - only conditioner.  This method seems to work well for curly haired people and can help minimize frizzies for those blessed with curls.  Usually an inexpensive conditioner is used like a shampoo then followed with a better conditioning conditioner.  This method can be used indefinitely assuming the conditioners do not build up too much on the hair.

The CWC method uses conditioner on the hair before shampooing, then shampooing, followed by conditioner.  The first conditioner is intended to protect the hair during the shampooing and minimize tangles. It would not need to be left on very long.  Using diluted conditioner seems to work well with this method.  This method could also be used indefinitely.

Don't worry about asking questions - I figure there are many others out there asking themselves the same questions, so ask away!