The thing with the autobrakes consuming hydraulic fluid is that the metering valve in the autobrake controller will continuously (spelling??) modulate the amount of hyd-fluid allowed to the brakes and the excess being sent back in the returnsystem. For the sake of argument, say you preselected autobrakes 2 , the maximum brake pressure allowed through to the brakes is 1750 psi and will be modulated so that the aircraft reaches a decelleration rate of 5.0 ft/sec/sec with all the means of stopping used (reversers and liftdump). That means almost half of the the hydraulic pressure=fluid is being sent back through the brake return pipes back to a potential leak in the R HYD SYS.
Whereas if you make the one application with yer size 11s, and you keep the pressure applied constant there will be no hydfluid going from the brakes via the return pipes back to the reservoir. It will all be locked on the supply side of the brakes.
Cheers