The Left4Dead sale also probably did well because Valve had not done many deeply discounted sales before. If they do these sales more often, people will hold o

The Left4Dead sale also probably did well because Valve had not done many deeply discounted sales before. If they do these sales more often, people will hold off purchasing the higher-priced game in anticipation of the sale; not only would Valve lose higher-margin sales in favor of lower-margin sales, but they would also lose the sales of people who forget or change their mind about buying in the interim. More frequent sales also hurt the novelty of the sales, causing them to be less widely reported and also less likely to trigger an impulse purchase.