Let's face it. Painting by numbers has another, shorter name--coloring. No matter how you do it...even after you apply multiple coats to keep the numbers from peaking through...you still have something that screams "I AM A COLLECTION OF PAINT PUDDLES!" (Not that there's anything wrong with that.)
With a Chirpwood Paint by Shadows® art kit, If you paint directly on the shadows and closely mimic the guide images, you will get as good or better results much more quickly.
BUT...if you want to work on your artist skills such as mixing paint, blending colors, dry brushing, wet on wet, stippling, etc., then Shadows kits are far more useful. And when you finish, your work will confidently proclaim "I am a PAINTING!"
Paint by Shadows® kits have art teacher approved instructions and short accompanying videos to help you develop your skills!