For humans, the more previous ones we know about, the better, because we have more chance of applying a model that works in the new environment. That's called "experience".
I've seen people apply their normal behaviour to situations that have changed, and then get totally confused (and angry) as to why the result isn't the same. Observe anyone travelling in a new country for examples ("why don't they show the price with the sales tax included here? This is ridiculous!").
In a perfect world, sure, we'd construct a rational mental model of a new situation and test it carefully to ensure it matched reality before trusting it, and then apply it correctly to the new situation. But it's not a perfect world, and people don't actually do that. Usually we charge in and then cope with the results.
Of course, I'm not saying that AI should do that. It'll be interesting to see how a "good" general AI copes with a genuinely new situation.
Imagine playing a game of Chess in which the pieces and rules gradually changed bit by bit until by the end of the game you were playing Go. That's much closer to what real life problems are like and a human child could absolutely do that. They might not be much good at it, but they could absolutely do it even without ever having played either game before just learning as they went. Note to AGI researchers, if your chatbot can't cope with that or a problem like it without any forewarning, don't bother applying for a Turning Test with me on the other side of the teletype.