The rotor won't keep spinning when you lift your hand. The mass of the wheel will allow it to spin longer. There should be a drag spec in the manual, and possibly separate specs with and without pads so you can check bearing drag as well. I don't know how it's checked in MBs but for a car I used to have you tie a cable to one lug, wrap it around the other lugs then measure with a spring scale.

Sixto
95 S420
87 300SDL