Recently I flew out of KLGB to KPHX early one Monday. It was a CRJ9 that was well worn and used on the inside. Later that week on Friday afternoon, I flew back from KPHX to KLGB. It too was used and abused on the inside, meaning the seat belts were frayed, the storage pouches in the seat in front had lost all elasticity and sagged, the carpet was dirty and slightly bare in places, walls had scuff marks, seats were lumpy and worn. Turns out from tracing the plane number on this site that the plane I flew on Monday was also the plane that took me home. In the interim, it had been all over the southwestern U.S. and into Mexico. It averaged six flights a day, about 90 minutes a flight average. It went into service in 2005.
So, I wonder that the odds were I'd get the same plane? It wasn't as if it kept going back and forth between Long Beach and Phoenix. It went to Dallas, Sonora, MX, Oakland, Salt Lake City, El Paso, Burbank, Tucson, Memphis, etc. Also, I'm going to gather six flights a day isn't unusual, but it sure did seem Mesa Air via American Eagle puts those planes to the test.