I replaced someone that gave their employer my name when they gave their notice. I was self employed and could start immediately. We worked together 3 days before they took their pto. It was not a smooth transition.

I onetime left one job to start another. After two Weeks, I was at work at my old employer (EY) at 6 AM to work uncompensated for 2 hours to help with the transition before crossing the street to my new employer (McGladrey)