I wasn't aware that Ryanair had 20-minute 738 turnarounds. As far as I am concerned, they are all 25-minute turnarounds - I do enough of them to be sure about that, and at 25 minutes, they are intensive enough!
As for not being able to use the correct delay code (it has happened to me, but not to that extent), if I really disagree with a given delay code, I will (as I have done several times) write a separate, full report about the turnaround to my OPS manager (and I will make sure he reads it, too!); if anything, I will have made my point about fiddling delay codes (after all, what are they for if they are not to be used?) and he'll realise that fiddling delay codes means wasting 10 minutes of HIS valuable time!
Cheers