Are space planes more efficient than rockets?

They are believed to be as the entire space plane is reusable instead of most of a rocket being discarded on every mission. However the space shuttle system was supposed to be more efficient than ordinary rockets because most of the vehicle was reusable, but it actually turned out less efficient for unmanned launches. One must be careful to consider all costs and tradeoffs and this is not easy for new not yet tried systems that might have unanticipated issues.