The systems capacity is an industry standard number that is based on maximum capacity. Not real world usage. In order to get the extremly high capacities systems are rated at, you would have to waste large amounts of salt. Your system is set at 10# per cu. ft., that is rare and not even allowed in many states that have efficiency standards for water softeners. Many states and localities have required that softener meet efficiency standards that require the systems to be regenerated at no more than 4 pounds of salt per cubic foot. The majority of companies selling softeners set their units between 4 and 8 pounds of salt, this is the "sweet spot" for water efficiency, salt efficiency, and water quality. The only time we recommend exceeding 8 pounds per cu. ft. is for applications that require a very high level of water quality, this would not even be able to be measured by standard test kits.
Hopefully someone will post a little cheat sheet shortly of salt usage vs. system efficiency, it has been posted 100 times on this site this year, but it never hurts to post it again.