DL 3012 then DL 2751 at JFK
Orlando → New York → Detroit
Timetable, New York time
12:00DL 3012 from Orlando at the gate
12:59DL 2751 to Detroit leaves the gate
59 min apart on the timetable
The last days
DL 3012 and DL 2751 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.