I did some googling but admittingly not much and will do some more, but decided to make this thread because I was surprised what I read. People are mostly suggesting to scrape more than just the peeling paint only if you're concerned with adhesion to the existing (not peeling) paint. I'm not concerned with it not peeling as long as it's clean and not a glossy finish (in which case I would sand it first lightly just to rough up the surface). A quick sanding of glossy surfaces is easy. I think modern paint should stick well and cans usually don't say it has to be down to bare wood to stick (might say it needs primer but a lot have primer included). I know you should always scrape off the peeling stuff. Some cans say if you just paint over it, it is more likely to peel worse. Scraping very loose chipping paint is pretty easy. I find the easiest tool to use is this [url=http://www.homedepot.com/p/Allway-Tools-2-1-2-in-Wood-Scraper-F4HD/202634546]Allway Tools 2-1/2 in. Wood Scraper-F4HD - The Home Depot[/url] If you're doing a whole house, they probably make wide ones of that ^ that attach to a pole. Anyway, I was surprised I wasn't reading about how people would suggest to scrape off everything to avoid having very obvious blotches/patches when you just scape what's loose and paint over it. When you just scape what comes off easily, you end up with a recessed area. The more previous layers of paint, the more obvious the recessed area. I just did a section of my wood soffit like this and it came out pretty bad but it's high up enough that no one would know. I just refurbished an older front door that had paneled glass with trim and glazed side windows. First, I scraped off what was really loose. IT had about 6 layers of paint already. My original plan was to just scrape the loose and paint but I did my soffit a few days earlier and realized what it would look like. It's probably more work to try and go back every day after it dries and paint the recessed areas but not the thicker areas and try and build them up to the same plane. I ended up getting a paint stripper even though I didn't want to use chemicals. I got the strongest stripper they sell at home depot and it did a terrible job. It's supposed to do multiple layers. I had to reapply it maybe 10 times plus I started using a heat gun which well out performed the stripper but is still very tedious and time consuming. I got it all down to the bare wood for the most part and then cleaned the stripper residue with mineral spirits and am letting it dry before it's painted. There are still some areas that have paint but it's such a thin layer that it should cause the recessed/patches I am talking about. if it does, then a second coat should fix it.

I have a few sections of different color paint samples on the wall. I'm guessing it will take a few coats of primer to cover them, but do I have to primer the whole wall each time, or do I just primer over the spots? I don't want to have different colored spots when I do go to finally paint the wall with the color I picked, so not sure what to do.