[Substitute "guest" in this posting for "client" and "account"!]
The era of seat-of-your-pants decision-making is gone. Even if you have great instincts, investigating the Voice of the Client is a powerful tool for avoiding costly mistakes, replicating your success, focusing on differentiation, building a client-defined roadmap to success, and for keeping your high-value accounts.
Source: http://www.raintoday.com/pages/1286_voice_of_the_client.cfm