That depends. There are some times when it works out just fine and other times when it's a little irking. There is one that I read as a teen where at the end of the story, they are trying to survive in the arctic and start walking. You never know if they survive. Or like, I enjoyed the end of The Giver, when they just slide down towards the settlement but I haven't read any others in the world.

Often, for a series, it is preferred that something is resolved to a degree in each book. There is the series big arch, but each novel in the series has its own little story arch. Or that is what I have heard thus far.