Expressing is a PITA! I had to do it in hospital inbetween feeds (so was feeding or expressing every 1.5hrs), to flush out her jaundice and because she was pretty small (2.77kg at birth but lost some weight).

Besides the hassle with it all, it increases your milk supply - when my milk came in i was comfortably full (think because i had only weaned DS 6 months early), but after a day of expressing i became pretty engorged and it was painful. Now it has settled down again. Although its good to have some EBM in the house, be careful not to do it to much, or you'll end up with some other problems.