DL 5641 then DL 1599 at Boston
Cleveland → Boston → Washington National
Timetable, Boston time
19:35DL 5641 from Cleveland at the gate
20:05DL 1599 to Washington National leaves the gate
30 min apart on the timetable
The last days
DL 5641 and DL 1599 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.