I have an office with two walls lined floor to ceiling in new thick mdf shelving. I am losing the will to live painting it, it's never ending. I did two coats of Zinsser bin, then one coat of supposedly one-coat primer undercoat. But that still looked quite patchy. And now I've begun the topcoat. One topcoat won't be enough, it'll need at least two if not 3. In total that'll be 6 times around the bloody room! It's exhausting! Is there not a better way? Top coat is eggshell.