For a fact I know of mixers in Chicago, Baltimore, Seattle and here in the Ft. Lauderdale/Miami area that never do features or episodic tv. There are ENG, EFP, corporate, infomercials, m-vids, local spots, etc. If you're in one of the major markets then you're a small fish in a big pond but if you're in a 2nd or 3rd tier market then you're a big fish in a small pond.
FWIW, I answered an ad for a sound mixer on "Craigs List" about 6 weeks ago and it's turned into a 3 year (40+ shooting days a year) job at a very nice rate + travel days.
Eric