Some Brake master cylinders Have to be bench bled, Some do not.
it is easyier to bench bleed them tho, And yes you still have to bleed the brakes after you reinstall it. Its impossible to keep the lines fully filled with fluid and install or remove the master cyl.
Bleeding at the master will not get out any air that is already down by the calipers. If you take an ASE test and say bleed the brakes at the calipers isnt required after replacing the master cyl you would be wrong big time.