Here in the North East…ANY small rust can turn HUGE in just a few weeks/months. It’s best to take of them when they are small before they get too big.
Fixing a small rust spot isn’t hard to do…making it look right is very difficult to do. That’s why insurance companies pay to complete panels repainted as opposed to just the small ding the bodyman repaired. It’s almost IMPOSSIBLE to just paint a small area and make it look right.
I’ve repaired many small rust spots over the years…But not too many in the past 20 years. Every now and then I’ve gotten stone chips that started to rust. If NOT taken care of quickly they spread pretty fast.
When repairing a rust spot…you’ll need to sand a area about twice the size of the rust spot to be sure you get ALL the rust. Whitey pointed out a product that chemically converts the rust. I’ve used this…but only AFTER I’ve sanded all the rust off. Then I put that stuff on. Then I may have to bondo or just prime…then paint. It’ll look fine at 20’ away or farther.