Hello!
...is that due to them not using idle power for the decent as the large jets do, think its for door seal inflation?
Certainly not, as the Bravo can easily maintain pressurisation (including the door seal!) at idle power. But unless you descend very steeply, it will slow down considerably on idle power. And because flying minutes are very expensive in our part of the world, we tend to optimise our profiles for flight time. A well planned continuous descent works quite well, giving you red-line speed all the way down at 1500 to 2000 ft/min descent rate and something like 60% power (N1) with a little over 400lb/min fuel burn for each engine. If weather and ATC permits of course.
Regards,
max