What Is The Listing REALTORS Strategy

A value added service I provide clients is to preview all homes that the buyers might be interested in. This way I only show them homes they will consider saving all time and effort. Well I was out previewing homes that showed on my clients radar. I called for appointments only to find that one was a non-confirmation. I actually called the REALTOR and was told that the house in not ready for showings and to come to the open house. I can do that because the open he is holding is from 1 - 5. Mine is 1 - 3 so I will stop by. My question to the listing agent was why was the home listed 3 days earlier if there weren't to be any showings till the open house. No answer other that come to the open. What do you think of the listing agents action or can you comment on what the strategy the listing agent is using. I would be interested in knowing your thoughts.