I'm guessing this applies to the first 6 flights you take.
I'm in a bit of a dilemma. Wife has 5 legs booked, 4 in CW/CE and 1 in ET. Looking at booking her to do LON-SOF and back too, but I'm concerned it means only the first six register. So if she flies the first 6, she'll lose the 5000 or so bonus on the last leg (was 5th, becomes 7th) which is long haul CW.
Deciding between losing that 5000 or getting the 2019 bonus for doing six flights. Only other thing i can see to do is to book her one way in RFS, but that means burning avios anyway.