The best way to view an open house is by considering it as one of many ways of marketing a property. Placing all of your eggs in one basket can often result in disappointment.
The best way to market any property is likely the one that places this option before as many people a possible. The more that are aware of any opportunity, the better the chance for success. Since open houses typically reach only a small number of people, it would seem that there may be better considerations.
You've likely heard of the real estte saying, "location, location, location." Well here's another one for sellers, "visibility, visibility, visibility."