Prepping a room to be painted is 100% perspiration, no inspiration at all; if you don't have the right products for the job.
While prepping my son's bedroom for painting, there was plenty of tough work to complete, before I was ready to crack open any cans of paint.
When I patch holes in walls, I do not use the newer, light weight spackle. I really don't like working with it. I am "old school" with my spackle, using the real thing.
Synkoloid's Spackling Paste is original, just like our forefathers' used. It does not shrink up, it is oil based and takes awhile to set up, before you can sand it and paint over it. About 30, to 60 minutes.
I like working with Synkoloid's Spackling Paste, because I can count on it, to do exactly what it is supposed to do. It patches holes and cracks in walls, without falling out later. It stick to almost anything. You can fill very deep holes with it. It also works on molding very well, too. It dries very hard, so I want to ensure it is pretty flush before it dries; or I will be sanding my arms out of their sockets.
This is the very same product professional painters use every day. If it is good enough for them, then there must to something to this spackle.