I've done manual labor and now I do skilled labor. I definitely couldn't do my current job stoned and I was definitely worse at doing manual labor when stoned but I still did it. I got lucky and never had any major injuries that would require a piss test for workman's comp, but I definitely smashed my finger and cut myself a few times with razor knives because I was stoned. I'd drop shit more often. This wasn't limited to me, my friends at work would smoke with me and all of us sucked afterwards lol.