Jim Parker's book "Do the Right Thing" describes the origins of the 10 minute turn at SWA. The airline had expanded to 4 airplanes, but was bleeding cash so had to sell one to make payroll. To operate the same schedule, SWA figured out how to reduce turn times.

Also, part of the strategy was to close the door and pushback while pax were still standing and looking for a seat. The pilots were not supposed to taxi with pax standing but some did. Herb fought with the FAA to continue the practice but lost the battle. At least one pilot was violated and fined by the FAA.

It also helped that SWA did not use aircraft cleaners between legs like the OAL's

A captain friend hired in 1976 stated that the elimination of the smoking section and the invention wheels on bags helped to kill the quick turns.