LAN methods are discovered to perform within the same building. However most institutions have offices located far apart from one other.
DISTANCE LIMITATION AND LAN DESIGN:
The highest cable length of a LAN is fixed because the electrical signal level becomes weaker as it travels. The delays have be short to allow access functions (CSMA/CD, token passing) work properly.
However in most cases a LAN requires to be extended layer distances than the max. Cable length size.