How much information do you really need to make a decision?
Some people want all the information there is to get.
Others are content to flip a coin with hardly any real data. The tradeoff is speed of making a decision balanced against making the right decision.
In my experience with managers, their decisions will be right most of the time if they have about 80% of the available information. Delays to wait for additional info may segue into "analysis paralysis" - an infliction that brings progress to a halt.
Think about your decisions. Most of them are easily corrected if a wrong path is taken. That further justifies that decisions can generally be made with less than 100% of the available information.
-Don Burtis