Bottleneck conditions in a LAN Environment

When testing for Bottleneck conditions in a LAN Environment, the first thing on my check list is how many Routers are used and then check each one's configuration. If the symptom being seen is poor bandwidth throughput, it could be caused by default settings of a router looking for certain type of protocol chatter that is not being used (example, AppleTalk), or it could be too many routers that can really drag down a network.