You may be wondering, "well it looks good in my eyes, why should I care? Surely, it will look juuust perfect."

NO!
Just like everyone, from professionals down to just beginners, you missed a few things that you could fix in your artpiece. As you keep drawing your piece your eye will grow to have a really large bias for what you've already drawn. This bias makes it exponentially harder to spot your mistakes as you spend more time with the piece.

If you flip your canvas your eye gets a new look at all the lines and shades in the piece, making it easy to spot that small mistake that may end up screwing with the final piece. This is especially important to do while drawing the first steps of said piece of work, such as while drawing the silhouette of a character which can suffer a lot from such bias.

Once you get in the habit of flipping your canvases you will receive more Twitter/Deviantart/Steam likes! GUARANTEED!!!

This concludes my guide. Flip your canvases...
Thank you and have a great one!