I recall many many moons ago operating a particular EDI-LTN sector. From
to start boarding to closing my L1 door was a grand total of about 7 minutes. Total turn time was 19 minutes.
Why so quick in getting them on & bums on seats? IMHO coz we boarded the pax from the rear door & doubtless had a shedload of regulars who knew the routine.
cheers
FF