Is it possible for more than one flight to have the same departure and arrival time slots?
When I was working at the FedEx hub in Memphis the pushback times were scheduled every six minutes from 1:48 to 4:00. That's 22 slots for well over 100 flights, so there were several scheduled in each slot. They were set up so only one aircraft in any particular section of ramp would be trying to push back at the same time. There would always be a queue at the runway.