Some families move more frequently than others. That can be a difficult concept to grasp for researchers who still live in the same area where all their great-grandparents did. The bigger problem is making certain that the same people have actually been located in different locations and that the researcher is not assuming they have the same person (or family) without more than just a hunch.
Making certain ages, places of birth, and other identifying characteristics are reasonably consistent is one way to reduce the chance of making an incorrect identification. Researching as thoroughly as possible is another way to be more certain that two people in records hundreds of miles apart are actually the same person. The more items that are located in each of the geographically separated regions, the higher the chance that one record explicitly connects the two individuals.