Let down

Does milk still come out in between let downs? My son usually nurses about 12 min on each side and during that time I can feel my let down reflex happen about 3 times with about 3-5 min in between. After the let down he usually just suckles, some times I can hear him swallow but other times I only hear him swallow during the let downs. Is he getting milk the entire 13 mins or not? He's satisfied after each feeding and has good weight gain so I'm not worried, just curious!