clamps in calculating box size

As part of calculating required box size, you count: 1 – for each hot and neutral wire entering the box 1 – for all the ground wires combined 1 – for all the cable clamps combined (if any) 2 – for each device (switch or outlet—but not light fixtures) When counting clamps, is this just the plastic type clamps that you can clip in? Most boxes already come with clamps included in them so are you supposed to count these as well? What if you only use 1 side or 1 of the included clamps?