The way I look at it, each chapter should accomplish something specific in terms of moving the plot forward. However long that takes is how long it takes. I prefer shorter chapters myself, but I don't think there is any hard and fast rule. Some of my chaprers were a couple of pages; others were much longer. Overall, I tried to keep them about the same length, trying to give the reader a lot of break points, especially for those who may be like me and fall asleep reading at night.
