LGDs are meant to be left in with the livestock and have 1000's of years of breeding to establish the protective instinct. As long as the pups are properly bred and raised with the livestock (or even just properly introduced as an adult) they live and care for their flock 24/7.
Herding dogs were bred for 100s of years to herd, which is a variation on using a hunting instinct. Very few herding dogs can be trusted to live in a flock, unsupervised, 24/7.
I own Kuvasz. When I moved to my current property and visited the neighbour's ponies she warned me they are dog killers. There were lots of farm collies and GSDs that tended to "visit" uninvited. The chased the horses for fun, bit and injured them. But the horses immediately loved my Kuvasz. They have a much calmer energy, and mover very quietly around stock so as not to agitate them.
The two types of dogs work very differently and have very different temperaments.