Gotta hand it to you
In art academies of the Nineteenth Century students had to master drawing of hands, feet and heads from plaster casts before they were even allowed to draw from the live model. With my fast paced, slap dash style I have always been pleased that such rules never applied for any of my classes.
That said, it is always good to have a little bit of discipline to help your technique.
The first two - quick sketches from the ASOC Summer Art Experience earlier this year - we drew our own left hand while the model was on a break, then we concentrated on the model's feet or hands.
The final one of the fist is from ASOC 2017, where each student took it in turn to do a one minute close up sketch of the model's hand.