The Sales methodology is a set of rule based activities which guide a Sales person to sell a product or services.
Hence, every organization, especially the Marketing and Sales Business Unit, needs to define it USP (Unique Selling Proposition) beforehand, including the Sales process.
This methodology needs to fit for your Customer and the Market segment, which you need to Target.
There are several methodologies like SPIN selling, The Challenger Sale, SNAP Selling, Conceptual Selling, Consultative Selling etc, hence it is wise to devise your own Unique Selling Process and then Amalgamate it with one of the Selling Model available from the list.
It makes Sense, because we try to get Business from a Dynamic, and continuous Evolving Market. So the Strategies and Methodologies, can be different for different circumstances.
As per Hypothesis, what is Right today cannot be the same tomorrow.
Hence always be prepared to Welcome Change with respect to your Sales Techniques.
Thus it Evolves and gets Optimized, from Bid to Bid, as Lessons Learnt from each Bid, do add a lot of value, to your next Sales Deal.