In a typical game nowadays, at 200 dwarves I might have 10 full time miners who also do masonry and engraving, but no hauling, another 10 masons and engravers, 5 or 6 woodworkers who do all wood related crafts and burning and maybe part time furnace operating, 5 or 6 animal trainers/caretakers, the most skilled 2-3 trainers would have no other labors besides training and leading crossbow squads and maybe butchery, tanning and leatherworking, so they get lots of time off or to train any animal that needs it. 1 or 2 full time doctors with nothing else besides bone carving, 3 or 4 nurses who have hauling and a craft labor, 10 to 20 smiths who also do furnace operating and the worst skilled ones would rotate in militia squads The rest would be crafters and farmers who also serve in rotating militia squads, but all the farmers would have one or two craft labors. I don't and never have had dedicated haulers, only a few critical dwarves (doctors and a few animal trainers and the best smiths, typically) and miners get hauling duties disabled. Everyone pulls levers, which I try to keep as close to the meeting halls as possible so some idling dwarf gets the job.
The idea is they all need things to occupy them besides busy work. Crafts so they can enjoy being creative, and military service so they can fight/train. But also breaks. Nobody needs every labor enabled all the time.