i have a "grazer" who is sleeping on my arm right now, so please forgive the lack of caps and typos.
She eats slowly and sleepily for 3 hours at a time, never getting full... and then will sometimes take a nap after that for about 20 minutes, then feed for another couple of hours. It never ends. the only relief I get is when my other half gives her a couple ounces of formula at night so that I can sleep for a couple of hours (and so can the baby).
We've been to a couple of different LCs and I'm trying various things to improve her latch and my supply. But the basic truth is... the baby is a grazer and is really slow.