I had a friend who lived in a flat of 10 people and for his meals he would wait around while everyone else cooked and ate what they left on their plate. If you think about it, I suppose 10 x leftovers would be quite sufficient! But I imagine stretching dinner over what could be 8 or more hours (given that students eat at weird times) would have been a little inconvenient.
For me, I just like buying things in bulk and shop's own brand goods. I had to; but it was my own fault for enjoying uni life too much at the beginning!