In days gone by disks did used to last 2 or 3 times the life of the pads BUT today the situation is different. Modern brake pads no longer have asbestos and they are a harder material. This does mean that disks don't last as long as they used to - it's a fact.
F30 330d M-Sport
F20 116i M-Sport for the wife
E90 330d M-Sport, gone but not forgotten