Flown them...
During the summer several travel agencies in south florida had contracts with them to fly to dominican republic on weekends 2 to 3 times a day. I got to fly on them during a 7 day vacation to Domincan republic. I spoke to the crews and they said that most of their flying is on weekend charters. Don't know if this was a summer thing only. Also, they seemed happy with the job. They said, like elsewhere it was not perfect or United wages, but it was ok.