How do you do so many rotations without building excessive speed?
It's a spin - by definition it doesn't build speed.
The aircraft is stalled, it does not accelerate. It's only when it comes out of the spin that it accelerates.
Our Spin Goddess Catherine has videos of extended spins in the 150-it's predictable and always recoverable. It's one of the best airplanes ever built for spin behavior and recovery.
