Actually there are very few "part time" on air jobs thanks to the PC and Satellite programming. Looking from the owners angle, why have "part timers" and the expense of hiring part timers who may or may not be talented or competent, when a PC some software and a satellite dish will give your station a "professional" sound 24 / 7. Plus PC's and or satellite dishes and receivers hardly ever get sick, have car trouble, get drunk, or end up in jail.
IMHO: These "savings" while helping the owners for the short term, will lead to end of "music" radio. Why listen to a radio station that is just a PC / Jukebox hooked up to a transmitter when a smart phone can do the same thing WITH OUT COMMERCIALS! Also where will the next generation of on air folks come from? Radio "schools" can teach some one the basics but where will the experience, polish and poise come from.?