If a crack is found the aircraft is grounded, period. What Boeing is basing its inspection schedule on is probability based on what they have found so far. This probably will change as reports accumulate. The three day reporting requirement should indicate how seriously Boeing views the issue.
Qantas is perfectly legal in it’s maintenance I’m sure. Whether it’s being prudent, I wouldn’t know. I would have thought if it was an easy inspection in passing it’s worth doing. If it’s cracked it shouldn’t be flying.
Im surprised that Qantas has “seven months” to look on low time aircraft. I would have thought 3000 cycles per year, but I could be wrong. 1000 cycles is roughly 4 months at that rate.