Priming over patched spots - I'm confused
I've been trying to figure this out from the information out there on this and other forums, but I'm seeing different answers or maybe not understanding the answers.
I am going to be painting bedroom walls, and there is a small area that needs patching. I'm planning on using BM Aura matte, and the color change is just cream to beige (latex over latex). The room has a ton of light, so any small differences in the sheen would be noticeable.
After patching and sanding, do I spot prime, and if so with what kind of primer? I've seen people say that if you shouldn't spot prime, but instead prime the whole wall. Others have said you can just spot prime with the same latex paint you're using to paint the walls and then it won't flash. Others say use oil or shellac over a patch. Still others say regular latex primer, because oil or shellac will look shinier under the paint.
I've also seen a lot of people say you don't need to prime at all, but I thought that the joint compound would be more porous than the wall. It's possible that the non-primers are assuming painting over a painted wall without any patching. I've read too much and gotten myself confused. Thank you for any help that will straighten me out on this issue.