Certainly not when you're using it with flash, in or out of the studio. With flash photography, the shutter is mainly used to control the ambient continuous light exposure with respect to the flash. Aperture controls flash exposure. The Mamiya RZ has a leaf shutter and leaf shutters in general don't go very fast; the fastest ones are found in the PQS lenses of the Rollei 6008 system- a mere 1/1000s.
And if you absolutely have to use ISO3200 film and continuous light, there are always Neutral Density gels to go over the lens.
As someone said above, stopping extremely fast motion is done by extremely short duration flash with no ambient lighting.
The Mamiya RZ is usually used for studio-type photography as their designers intended where flashes are used and fast shutter speeds unnecessary.
No one camera does it all.
Some of my cameras have only 1/25, 1/50, and 1/100. I don't even find that limiting!