As long as the water quality is to her liking (which it seems to be) and she is getting enough nutrition to grow the eggs, she can produce them on a monthly basis. Some species can turn it around even faster, but in my experience its seems about once a month. Even when they eggs are fertilized they turn it around pretty quick if the , I have a couple of females that seem to be holding again only a week after having released the fry. I try to strip those really early every 3rd or 4th time (I don't keept those eggs) and keep them separated form the males for a few weeks to allow them to eat for a while so they don't loose weight.