Getting old and even having experience in one particular field doesn't automatically provide wisdom. It took a long time for my father to finally admit that his experiences and the world he grew up in are so different from mine that a lot of his experience no longer applies.The wisdom of age and experience should have been able to keep the demons of ambition in check. She deserved better than that kind of legacy, IMO.
People who are wise from age and experience don't just get it by default. They keep on top of what's going on in society, use what they know from before still works, and throw out the things that no longer apply. That's why from what I've noticed the people who like to go on about their age and experience are usually the last to know anything about anything. The fact that by their tone they seem to be coasting on the "obvious" experience they already have from their age, they *aren't* keeping up with the latest changes in the world and their knowledge becomes irrelevant. Usually the old people who know their stuff aren't the ones bragging, even passively, about age and experience--they know that the world is too dynamic and changes quickly and you have to actively keep on top of it, and there is no set point where you're like "I already have all this experience, I've seen everything, etc."
Shelby *was* someone who kept on top of all the latest changes etc. That's why she was a Borg expert in BOBW. The problem is, because her goal was to get to the top, once she got to the top she probably didn't keep up with the small details and changes in Starfleet etc. other than what she needed to.