As long as you know your stock you are working, crowded pens are a fabulous place for the dog to get up close and personal to their stock and gain confidence. I don't interfere other than to give some direction. Kilt is the queen of the pens, so it's time for her to pass the baton to Yoko.
I'm lucky that some of the time when I go to Task farms all of the goats and sheep are in one rectangular pen. Sometimes, I'm really lucky (like yesterday) and the jenny isn't in with them. :0) Yesterday a billy goat turned on Yoko and she gave him a hard bite on the nose. I usually see Yoko try to turn her stock by grabbing a heel. But, in these crowded conditions it really was not conducive for her to try to do that, so she clomped him one on the nose. Just another tool in her tool box. I like my dogs to get in close enough to feel the stock, to be able to sniff them, and get more comfortable in tight quarters.