I think the only person capable of judging their state of fatigue has to be you. Just because some requirements have been met or not met is surely irrelevant? This was discussed to some extent in the other linked thread.
I noticed in a recent accident report that in summarising the various crew (flight deck and CC) on board at the time of the incident, the rest time preceding the flight was recorded, eg: 12hrs rest, more than 2 days off etc. That must mean that it's considered important.
A recent thread (sorry can't immediately locate it) said "just report that you're fatigued and cannot fly". A huge contradiction exists here if you were to feel your job is on the line if you don't fly, but your life (and that of others) is on the line if you do.