Flat rate pay is based on the estimate. Say a bumper pays 5 hours to paint. I get paid 5 hours to paint it. If you're efficient you are generally 200% efficient. That means I turn at minimum 2 hours for every hour I work. 24 years of experience is beneficial. Prep and paint 4 bumpers in the morning you just made 10 hours in 4. Do 4 more in the afternoon and you just made 20 hours in one day.