I don't do it but have worked on places that did.
You need to be able to rotate grazing, have low stocking densities, and really you need cattle too so you can graze cattle then sheep then cattle, so each species eats each other's worms.
I think you would also need to be turning lambs out onto pasture which hasn't seen lambs for at least 12 months.
If you are in a fluke area you will struggle to keep them fluke-free, unless your ground is especially dry for the area.