A "Pack horse" is a variety of sawhorse with canvas nail bags on the legs. Usually, you make them on-site and those that do not survive the project, pitch them with your scrap wood and be done with it.
I rarely use sawhorses as a carpenter: I work on plates (the tops of walls) flipping trusses and setting joists. Usually we apply sheathing and even paint the walls long before we tip them up. That way it's a lot less work after erecting the walls.
Pack Horses are handy on the floors, though. Save yourself a lot of rummaging around and build them to suit whatever you're doing.
