Painting one panel at a time?

I have a 74 Dart Sport that needs some body work & paint. I talked to a very reputable body guy about him doing the work. Due to the lack of funds to get it all done at once he suggested he do one panel at a time. He said he could repair the fenders first & then paint them. Then when I'm ready to do more such as the doors ect. He would do them in the same manner. He thought that painting them in sections would work. The paint will be a basic eggshell white. I would keep the paint in the meantime.
My question is: Has anyone done this to their car with good results?
I think I would rather he did the repairs & leave it in primer but he seems to think that painting them at the time of the repairs will keep them from rusting in between the time it will take to do the whole car. I am guessing it will take two years to get it done this way. It is always garaged & I have been finishing the undercarrage in my spare time. I can never seem to save enough money to get it all done at one time. I always seem to find n.o.s. parts that I can't pass up.