Eh, sometimes people switch back and forth depending on content. Alts get better geared than mains for one reason or another and people have '2 mains' or they try to keep 2 classes equally geared and played for one reason or another. I had a friend who hit 50 on PLD and BRD (as his first 2 jobs to 50) within a day or so of each other because he kept switching back and forth while going through the main scenario.