Surely the point here is not whether you will or will not but the fact that crewing or some management pilot is trying to make your mind up for you, before the last sector has even been encountered.
At a certain loco out of EMA and MAN you are quite literally told before you start on the the first of four sectors that YOU WILL extend duty into discretion. When you politely decline you are then phoned by the most senior of pilots, ranted at in no uncertain manner and told what you "will do". At no time are you expected to have an opinion.
What is clearly obvious is that Pilots dicretion is being subsituted
for extending FDP at crewing's dicretion.
I always thought that you could not plan to go into discretion at the beginning of your FDP, end of story..or not as the case may be!