At the end of the day I thought the question was not "why was my speed wrong?", but "Was I wrong to increase speed?" - IMHO I would say that as long as you allowed for the higher fuel burn then there is no reason
not to do this if you want to - if not then your drift/time calculations will be wrong (though to be honest, not enough to really be significant).
I would be interested to know their arguments for
not increasing speed.
