<When not more than one hour from destination the wx at destination is CAVOK, two runways available, ATC have advised no delays expected, wx expected to remain CAVOK for at least an hour after ETA etc. etc>
<3 mins away from a MayDay does that take into account any possible provision in your Ops. manual for reducing reserve fuel prior to arrival at your destination?>
BE, I do not know the detail, but I SUSPECT 'yes' to the second, and that this had already happened; in Pandora's case, '3 mins away' was probably 3 minutes from the 30 mins reserve, (which JAROPS alleviation you mention).
Pandora will, no doubt, clarify, but the question asked was about the ethos of departing with less than flight plan fuel - not really what happened thereafter, but what could have been REASONABLY expected to happen.
To be strictly accurate, of course, I do not believe that 'reserve' fuel can ever be reduced - unless the a/c weight changes dramatically.