CRM Returning customer

How is a returning customer (for the same sale, often takes 5-10 visits and calls) noted. This is vital to correctly calcutate the total $ potential & Close rate of all leads, whether walk in, LMS, call in , Coretec White Glove etc. This can then follow through opportunities, qoutes, etc. It needs to start in To do. Unique new customers are very important but total traffic is also.

CMM has a repeat inquiry box to check of for this. CRM need the same.