althenines,
normally 500 fpm is fine, but do please remember it's a minimum. sometimes you come over at a release level of 120 but because the aircraft below have just been vectored off the hold you are cleared down to 80 straight away. in this case we do need a high rate of descent so the aircraft above don't miss their place in the queue. if you are cleared down through two or three stack levels, why not pick up the rate to nearer 1000 ?
at the end of the day if we do want a high rate of descent we will ask you to EXPIDITE