One way to check the shocks would be to take the car for a ride of 5 miles or so on a normal road, then check the temperature of the shocks. Let them cool if possible, then do 5 miles on the road in question, the shocks should be noticably warmer, if not , they are not working.

Your shocks could be "pumping down". Many, frequent bumps can move the fluid through the shock's valving, but there is not enough time for the fluid to return fully to be ready for the next bump.

I had a Honda dirt bike that had shocks that would perform fine until I took it on a stretch of RR tracks, soon the shocks were "dead" and the bike was squatting down in the rear and bouncing around. I had read about this problem in Cycle magazine.

There is plenty of force from the bump to push the shock up, but only the car's springs and pressure in the shock push it back down.
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96 855R, 95 855,854, 90 744 Ti - 325,000 miles driven