We don't necessarily rotate pasture now, although when we had a higher stocking density we did. Now we don't have a problem with worms - we worm individuals if they look peaky or scoury (not often), and we do the whole lot before tupping, usually - which is scientific nonsense as apparently they shed worm eggs much more when they lamb. For us, as our sheep lamb on their own in the fields, worming them then is very hit or miss, so we do them when we know we have them all in, in Nov - in a couple of days time in fact. Ideally you should only worm dependent on FEC results, especially if you have a high stocking density.
The only other time we worm whether they need it or not is when we are selling animals, to make sure they go to their new homes clean.
We cut our own hay, so we put the newly weaned lambs on the aftermath, while their mothers are drying off on a less lush pasture, but that has only been free of livestock for five months max.
Most of the time, apart from having some small groups in separate fields for different management, we let the main flock move itself around and choose where to graze. With only a small flock now, that seems to be successful for keeping worms down. I'm sure that letting hens free range over the whole area helps too.
I have a feeling that rotating pasture is left over from when the whole flock was weaned at regular intervals, then moved onto fresh pasture. That is no longer recommended. Really, the only truly effective rotation is to be able to leave whole pastures fallow or unoccupied for at least a full year, to break the worms' life cycle, or to put a different species following on, such as sheep after cattle.
I think most people will say that rotation is essential, but in our specific circumstances it doesn't seem to be.