The answer may depend upon the sheer volume of prospects you are working with, as well as whether you are cultivating one-shot sales events or repetitive business. However, for me each potential customer is an independent project and my N/A is to make substantive contact in person, by email, by phone, etc. The successful outcome of the project is almost universal, which I express generally as:
Successful outcome = "Customer (xxx) is an engaged, satisfied customer"
This means there is an ongoing relationship of some type with the customer in which they & I are currently satisfied with whatever is going on with that relationship.