[YorkshireLass]

Repeated dosing with the same wormer group and immediately moving the sheep to fresh pasture has led to almost complete wormer resistance in Groups 1, 2 and 3 wormers in NZ.

This is an important note.
If you worm and then move immediately to fresh pasture, any worms that have survived the drug are now free to colonise this nice clean pasture - and they will, because they will have no competition from drug-vulnerable worms.