My sister lives in San Antonio. Everytime I jumpseat to visit, it seems I am the only one on an Airbus with 6 or 7 seats. Maybe I am just lucky.
Weekdays.
MEM-SAT. Two afternoon flights leave MEM around 3:00 pm (Airbus and -10, so around 10 or so seats total not including the cockpit jumpseats). Late night also two flights (Airbus and -10, one goes through Houston).
SAT-MEM. One morning flight and one evening flight.
I would guess the Moday night jumpseat into MEM fills fast.