BH has farmed sheep for over 50 years, up to 400 sheep running on the farm, never had a sheep crush.
For dosing / drenching / jagging it's best to have a 'treatment race'. Opinions vary as to what width and height is best, some like it so narrow only one sheep at a time can be in it, the operator is outside and leans over the sheep to drench it; others like it wide enough to be in there with the sheep; I've also used wider yet ones but then you do need to mark sheep as you dose them in case of a mix-up.
The key thing is to have enough sheep in the pen/race that they don't have much room to move, so you don't run about catching them, you just squeeze alongside them!
Best thing is to experiment with movable hurdles up against a wall and find out what works best for you before investing in anything more sophisticated / permanent. Ideally you'll want solid panel hurdles for the section in which you are dosing the sheep; railed hurdles for collecting / routing and other penning areas are fine.
Here's our treatment race - you can see that it isn't wide enough for two sheep side by side. We do all our dosing here.