I would say 1/10 randomly hired people are suited for harvest/trim work, the rest is wasted labor dollars. Basically if you find someone good try to keep them.
Fastest dude I’ve ever employed can knock out 5 lbs a day (big nuggets totally stripped). I would say the average in general of people who manage to last is 1-3 lbs a day, depending on the material. What it boils down to for me in a hand trim situation is pay them well, and have food available, I’d go as far as to organize a daily lunch/meal. You can’t expect an 18-20 year old dude to remember to eat all the time, well fed people you get far more productivity out of.
As far as machinery goes I only have direct experience with trim bros machines , they do shave brittle material really hard. Honestly forget the productivity because I wasn’t running the show. My flower I wouldn’t ever throw in a trim machine, but I’m not pulling 1000 lb+ harvests. If it’s nice craft, good quality flower my opinion is find good employees, and create an environment that fosters productivity, you don’t have to necessarily pay people $20/hr and/or $150+ a pound (if paying by unit) to get high productivity labor.