Quick rule: if the total repair is less than your deductible plus expected premium increase over 3 years, pay out of pocket. For most $500–$1,500 fender benders, that means cash.
Use insurance when: you're not at fault, damage is over $3,000, there's any injury, or the other driver is uninsured. In every case, get an independent estimate first — insurance-preferred shops often quote to their lowest acceptable spec, not to yours.