BOAC
I understood GlueBall, only I disagree with him.
I know there are many different cabin pressure controlling systems for airplanes.
However, if it is required that airplanes reach field pressure before landing, the time to descend from crusing level to the airfield is the same as the time to increase the cabin pressure from its cruising value to airfield's.
So we have a time (descent time) and a pressure change requirement. These determine the average cabin rate of descent. Rapid descend, faster average rate. Slow descend, slower average rate.
As Captain Pitbull clarifies, if the cabin rate is fixed by the system and you dive like an Stuka, you will either reach the cabin (and from then on the cabin and airplane's rate are equal) or land with differential pressure greater than zero. I think that after touch down, the outflow valve will open in most airplanes, so in the latter case the cabin would unpressurize very quickly after landing.
The result would be in any case a faster average cabin rate of descent.
I do Valsalva very often and always block the other ear, otherwise can be harmful. I prefer doing it very slowly, too.