This is just a sample from a great post by Jaqueline Kent:

The breastfed infants, who were all growing normally, cued to feed between four and 13 times a day. Some of the infants (13%) only ever fed from one breast during each breastfeeding session, while 30% of the infants always fed from both breasts during each breastfeeding session. The remainder sometimes fed from one breast, sometimes fed from both breasts, and occasionally had a ‘cluster feed’, going back to the first breast after finishing feeding on the second breast. For a 24-hour period, mothers measured the milk intake of their infants by weighing their infants before and after each breastfeed, referred to as test-weighing. These data showed that rather than taking the same amount during each breastfeeding session, the infants consumed between 0 mL (the infant went to the breast and apparently suckled but removed no milk) and 240 mL.

Babies can nurse in lots of ways – it’s important to remember to define success in the outcome (thriving babies and parents!) rather than a one-size-fits-all description of how a baby “should” be nursing at any given age.