This is such a wonderful and common question. It can be considered normal for babies to go back and forth from bigger gulps to light suckling throughout a feed. Essentially what they are doing when they lightly suckle, is calling for another "let down" or heavy flow of liquid GOLD! Signs that a baby may be done are they release from the breast on their own, relax their fists and body, are seemingly relaxed and content, your breasts feel "emptied", baby may be sleeping. Specific signs of feeding efficiency vary so greatly from baby to baby and feedings may even vary from feed to feed. Since it is so variable, it is always best to respond to hunger cues and feed on demand while looking at the milk transfer as a whole. We know babies are getting enough breastmilk when they have at least 6-8 wet diapers with some juicy poopies within a 24 hour period, are gaining weight daily and pediatrician is happy with growth and development.