I didn't say they don't happen. They're just so rare that the difference between ~6h rebuilds with 4T spindles versus 15h rebuilds with 10T spindles simply doe

I didn't say they don't happen. They're just so rare that the difference between ~6h rebuilds with 4T spindles versus 15h rebuilds with 10T spindles simply doesn't matter. Any homeopathic advantage of slightly faster rebuilds is dwarfed by the benefits of higher density (less hardware per capacity).