Dear Glueball
The average cabin rate of descent during a descent exclusively depends on the cruise cabin altitude, the airfield pressure and the descent time.
No matter if you have packs or are flying in Von Rishtoffen's Fokker. In the 747, an automatic system will manage the outflow valves so that the cabin V/S will be confortable (typically 350 fpm). In Von Richtoffen`s Fokker it is the airplanes V/S which determines the cabin rate. In both cases, the TOD can be a factor affecting the location of the TOD, or the descent method.
From 7,000 ft to sea level in 20 minutes the rate is 350 fpm. If you descended those 7,000 in only 10 minutes (I know this would be quite a kamikaze descent, but please allow me such didactic treat) then the average rate would be 700 fpm. Many cadet pilots understand this the first time I say it.
No matter what you do or what kind of plane you are flying you have to reach sea level pressure before landing. You cannot land in 10 minutes and wait another 10 until the system reaches sea level pressure. That is the problem. That is a reason why some airplanes cannot descend at idle all throughout the descent but they have to maintain a given vertical speed or thrust setting until reaching a FL from which they can retard the throttle levers. If they didnīt the target average cabin rate would be exceeded.
It is a fact that if you descend too fast ( or faster than planned) you will have a higher cabin V/S than planned. Even at 500 fpm you may suffer pain if your ears are sensitive. In addition, when the average cabin V/S is high there are peaks, so an average 450 fpm descent can be 300 fpm in the beginning and over 550 fpm at the end (this is the moment when the little babies cry).