Some psychologists will tell you that it's because they're being social, as being social is in a womans psyche ie women have historically been the child rearers and have done so in a social group and this wittering on (!) is just how those social groups sort out the social knowledge which they've acquired of late. This is because women need to work out social structures and orders within the group so as to be prepared for any social eventualities. Whereas men haven't been so socially inclined, have often been outsiders. Personally I also find what you describe as incredibly unstimulating. Apparently, women doing university courses are no different, something many men complain about. I know an old lady who sometimes phones me up and literally tells me everything that happened that day, from who said what eg "The doctor said sit down, how are you and I said oh doctor, I don't feel" etc etc, to the weather was so and so (after butting in on me). Whereas If it's me explaining that I went to the doctor, then I just say "I went to the docs, he prescribed so and so"- end of! So if this really is because of the psychologists theory of social workings out or if it's because of an unempathetic ability to realise that she's boring me to death, i've no idea. I suppose it also depends on what interests people. I reckon that most people are literally trained to be boring!! They watch dumb tv, listen to dumb radio, do dumb things and don't think about the bigger things in life, which are important and interesting. My mum thinks that cleaning everything has been her role in life, 'cos she's been trained for that role. All she has to talk about is how she cleaned a food cupboard etc.
If I were you i'd tell her that you don't want to know and to "cut to the chase". Also tell her that you find it dull. If you don't, then she won't know and will just carry on!! I've done this before and they slip back into the wittering on, so you have to remind them . Say "Cut to the chase"!!!!