The OP implies that there are no males available, in which case he will never see eggs, only saddles. In this case, the question of whether or not mature females still produce eggs is moot. I think there is a cause and effect issue with his original observations of why he's not seeing berried females. It has nothing to do with their age. A tank full of females that are just entering their brooding age will never show eggs either if there is no male present to fertilize them.