Know exactly how that goes. Fixed a quarter panel on my old truck and three days later I had the whole thing stripped down in my driveway. Once you start seeing the potential, it's hard to put the tape gun down. You're already doing the hard part with the repair, so laying new color over the whole thing starts to make perfect sense. Just be ready for it to take over your life for a few weekends.
Totally get what Eric means about it taking over your life. That one repair spot makes the old paint around it look even worse, so then you're sanding the whole panel, then the door next to it looks off. It's a real domino effect. Before you know it, you've bought a respirator and are looking at paint guns online at 2am. The real trick is figuring out if you have the space and time to actually live with a car in pieces for a month. What color are you even thinking about going with?