Positive ease is a phrase that mystifies many knitters. Louet's post (What's a Positive Ease?) explains exactly what positive ease is, and how to choose your ideal garment size based on your personal preferences for fit.
Some projects are commonly pushed aside once they are off the knitting needles or the last crochet stitch has been made. All the garment lacks is buttons. . .but it may take weeks or months to do that simple task.
Taking Time to Smell the Roses' technique might help save garments from the buttonless fate - add the buttons as you knit or crochet the garment.