Repainting a metal fence?

[Nat C.]

I bought a property with a very solid and secure 8 ft high fence. I'd estimate is under 80 ft wide. We are currently in rehab stage. Only cosmetic work is needed on this one. The fence is around 5 years old. The black paint is chipping off and there is rust in some places. I know the proper way to fix it. All the paint needs to be scraped off, the metal cleaned down and a primer applied. Then a fresh coat of paint applied. We are really pressed for time here and I'm thinking of just spray painting over the exiting surface with a high quality, rust resistant spray paint. Do any contractors know how long it will last and if I'm just being foolish cutting corners? I'm struggling to make a decision on this one.