I work three full days one week (out if the house 7am to 6.30om) and two evenings the next week (away 2.30pm to 1am) and we have been just fine. The first few weeks I had to express for comfort but otherwise, the girls have coped just fine and my supply hasn't been affected as they make up for it when I am around. This started at about 11 1/2 months when I returned to work.