NASCAR Question

As a fan of motorsports, I occasionally watch NASCAR, although I much prefer
F1. I often make the analogy that F1 is to Nascar as chess is to checkers.
(-;

While the F1 cars seem to be deftly piloted around the course, NAS-cars look
like the are being driven by wild teenagers just trying to constantly keep
the pedal to the metal without spinning out. Witness the number of Nascar
spins and accidents, probably more in a couple of races than in an entire F1
season.

What really puzzles me is why do they have to constantly be changing
suspension/tire setups during a race? Can they not dial it in after practice
and qualifying? Cars that are "running well" do this once or twice during a
race, while those that aren't seem to come in several times to add or take
out some air, wedges, etc.

Am I missing something or is this just the American pee-nuckle of
engineering?