Cosmo not personal at all, but i spend a lot of time training pilots to adhere to company procedures and along comes someone who makes it up as they go along, there is no doubt your knowledge is deeper than average and to answer your other question i take the fuel required no more no less, the required being what i need to operate the flight safely sometimes that is plog fuel sometimes more and sometimes less (our plots use longest SID/STAR)
If the FMC entered mass is correct i.e. actual then the FMC will normally provide you with the most efficient CRZ level taking into account fuel burn, maintenance, & so on, our company guidance is that a 1000 below OPT is normal preferable than a 1000 above and we have had 2 high level upsets.
My point about CRM is simply that every time an F/o comes along and says "well I was flying with Capt Kirk and he said the FMC figures are guesses/rubbish/tool/just a guide" and guess what its the same names that keep cropping up, anyway enough drift
We are all agreed that reducing thrust at high FL to idle is not good and that gentle application of speed brake is what the manufacture recommends to address transient unintentional over speeds
