As genealogists often rely upon the memories of others, it's important to remember several things about memory and the memories of others. And even if you are a genealogist, your knowledge of these events is not firsthand and is subject to the limitations of the records used to obtain the information. Martha was not there for their births and marriages. Their deaths might have occurred a distance from where she was living and her memory of these events might not be clear. Again, while the dates may be accurate, it is best to remember that Aunt Martha is probably a secondary source for these dates and events, unless she kept diaries throughout a significant part of her life.
Time plays a big factor in the accuracy of memories.
Time should be kept in mind when someone recalls a story told by a long-dead relative, or remembers details about an event that took place fifty years earlier. Your ancestor who had a large family may in later years remember the children in their order of birth, but could easily have forgotten exact birth dates. I only have two children and have enough difficulty remembering the year in which each of them were born. I can only imagine the difficulty if I had twelve. It must be remembered that our society is much different today than it was one hundred years ago.