I have used one up until this week (12 weeks) for for the left and for about 3 on the right as Adele was a prem and my boobs are huge so she was unable to breath when she latched on properly. She let me know when she no longer needed it on both sides, and she is now able to feed successfully on both sides.

I was advised by the hospital to express after using the sheild though to maintain my supply.