Both my goatllings are from a high yielding BS line, they started developing udders and the billys owner told me to try and avoid having to milk them, so they don't get much concentrate, just a small handful of coarse mix to keep them happy when I feed the mums. I was told they could stop developing properly, they did have cute little udders, but I resisted the temptation and their udders never got too big and hard, the girls are now a good size and I'm looking forward to see how they do next year with babies.
One milker I've dropped to once a day, she's dropped to about 1/2 litre, the other is still on twice a day, but I'm needing the milk for a couple of lambs, and the house.