It is also important to realize that it isn’t merely “why” you are updating your will, but “when” you are updating that can make all the difference. Acting too late (or too early) may mean your changes are no longer appropriate or even immediately invalidated.
For example, did you name someone as an heir who is no longer in favor with you or—worse yet—has died? Who should get what they would have gotten? Are there now new people in your life—be they family members or not—whom you might wish to share in what you may have?