I wrote a post earlier this week about the failure of mental models leads to a political party becoming disconnected from reality, and thus failing to make accurate judgements. This was a narrow example of a wider point, that mental models often become detached from reality over time and people don't recognise that what was true yesterday could very easily not be true tomorrow.
I found a comic recently which illustrates this point rather magnificently (all credit goes to XKCD clearly):
Now, clearly it would be very hard for anyone to be unable to adjust their mental model for the situation as it will be post election in America, but this illustrates the key point, models shift over time, and by shifting they make the assumptions that went into them irrelevant.
They also prove that historical precedent is only of limited value when it comes to identifying future patterns of behaviour. The historical factors which went into creating the situation can swiftly fade, as the situation which created that truth may have already shifted.
If your model for identifying reality is based on precedent then it is likely flawed. Mental models need to be maintained in a form which will link them to current reality, or as close to that as it is humanly possible to get. Although the past may form a guide, your own interaction with the current state of play means history is not going to repeat itself.