Personally I think that shadows are a matter of personal preference. If you like your LOs to look hand scrapped shadows will take you a long way towards a realistic look. And that realism means that any that would have a shadown IRL should have a shadow in your LO. So when I'm scrapping for a paper scrapped looked all my elements (other than the BG) have a shadow.
That being said... if you like the way your LOs look without shadows, do it that way. This hobby is really about creating LOs that you like about memories that you want to treasure.
Here's a DIP
tutorial that should help you get started with shadows.
Good luck on the album for your grandsons!