Thats the most often used method at shops. Have done it plenty of times and works like a charm. You usually only have to turn the wheel to one direction and hold it there while the procedure is done. Suck up fluid in resorvior, put new fluid, direct return line to an empty container, turn wheel to right/left (cant remember), plug return on resorvior, be ready to pour fluid in at the rate it leaves the resorvior/fills empty bottle.
You have to be pretty accurate when pouring the fluid and the guy at the key needs to be ready to switch it off quick before you make a mess or run out of fluid in the bottle cos you poured too slow or ran out.
In my mind hand cranking allowd fluids to mix too much compared to pumping at idle. Itll either take too long or waste a lot of fluid in the process ... aint nobody got time fo dat!