How often should I replace my shoes for sprinting (spike shoes)

I have nike rival zoom sprint, they're beginner sprint shoes $75.

I have been using them twice a week since july. At about 200-400m a week since. Some weeks its more than 400 (like 500 ish)

What guidelines should I have to replacing them?

I googled how to test (twist) and they twist easily

Twist Test

Grab heel + forefoot → twist the shoe.

New Rival = pretty stiff, resists twisting.

Dead Rival = twists like a trainer.

If it bends more than 20–25°, plate is fatigued.