... ... some days 20 seats free, some days 0 ...
Qantas flight availability published to GDS's only indicate availability of up to 9 for sales in each booking class.
e.g.
... Y5 B5 H5 K5 L0 V0 S0 N0 O0 Q0 X0 E0
This indicates Qantas are willing to make available 5 seats for any of Y/B/H/K/L class bookings - it does not indicate 20 seats are available for sale. In this example, if someone snaffles an H seat, it would likely change to the following:
... Y4 B4 H4 K4 L0 V0 S0 N0 O0 Q0 X0 E0
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