Scott immediately increases the face value of a new stamp to make it a catalog value when they list an item. Used stamps vary greatly in catalog price. Stamp value is related to condition of the stamp and how much demand there is for it. A lot of older U. S. stamps can be bought in packets or lots of 100 or more for a price well below the catalog value. But the catalog value is a good method for the exchange of stamps with other collectors.
Every stamp collector uses a stamp catalog.
The majority of collectors in the U. S. own a Scott Catalog and may use them as a check list for what they own and need. So, it is important to learn to use the catalog.