We use the white ones when the lambs are young and then we move to the red ones, had 12 lambs on our shepherdess at the same time last spring and the teats would last maybe a week, which wasnt so bad
we found that if the milk was lovely and warm they chewed the teats more, when we turned the thermostat thingy right down to just above cold the lambs regulated themselves much better and didnt shred up the teats so bad.
So if lambs are under 3 days old we had the milk warm, and then over that turned it right down, seemed to work well, the lambs looked great and werent really any different to the lambs on the ewes, some of the cades were even better!
Also the shepherdess recommends abrupt weaning at 5 weeks of age, I kept ours on till 6 weeks but any older and maybe the teats get shredded even more?