AA 2591 then UA 1473 at Miami
Boston → Miami → Newark
Timetable, Miami time
08:37AA 2591 from Boston at the gate
15:18UA 1473 to Newark leaves the gate
6 h 41 apart on the timetable
The last days
AA 2591 and UA 1473 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.