I really hate that that this is true, but the key to a great finish really is in the sanding and prep. I loathe sanding. I really do. Here are two of the drawer fronts in a rather un-glam before and after shot.
Here is another after the sanding step and after one coat of primer. Yup you have to sand again, and again, and again. So far, my process has been: sand primer, skim coat of MH Ready Prep, sand, prime, fill in any missed spots, prime. My goal is a piano smooth finish. I don't want my doors to look like I threw on a coat of paint.