Can you put on a new flaxseed oil layer (whether oven or stovetop method) as you go along cooking with your pan, in other words over the splotchy stuff, or are those methods only to be used on a newly stripped surface?
Got a Matfer carbon steel pan. Got factory coating off with sandpaper like I was stripping paint (only thing that worked, not "potato peels," not "hot soap and water," not "bake at 300 for an hour."). Did 6 layers of flaxseed oil as per Sheryl Canter's blog. Absent-mindedly added some lemon juice (so focused was I on "tomato") at the end of cooking my first thing, saw lots of silver metal again. Cursed self. Inveighed against self. In week following, kept cooking other things. Now have mixed surface.
2 photos of the pan, showing different glare conditions since that makes it hard to gauge. Surface is pretty smooth to the touch. Started thread specific to this question since I didn't see it addressed elsewhere.