Originally Posted by babymog

The better the fuel filter, the longer the life. Other than that, it's just a matter of how much fuel has gone through it, city miles use more fuel/mile than highway.

As FI mentioned, they should be tested periodically. My local guy cleans/tests/adjusts for IIRC $25/ea, then they're all balanced and known-good. Usually this is all that is needed, but they can wear out also.

edit: Some fuel problems will also kill them, an example being fuel conditioners that suspend water in the fuel, can cause corrosion if water/fuel solution is left in injectors when parked (hint: buy good fuel and let the filter do its job of separating water).