Hmm... I've never heard that one, but that doesn't mean anything. There's lots of stuff I haven't heard. Anyhoo, I've night nursed w/both of my kiddos since they were itty bitty. I got my first PPAF when dd was 18m old and w/ds when he was 8m old. My dd took to solids much more than ds does and night nursed until she was 2.5yo. My ds is still night nursing at almost 20m. I've always thought from talking with friends who EBF and co-sleep that it's just one of those things that varies from woman to woman and child to child.