I will admit that there is one type of worksheet that I used in the past and found relatively beneficial, although it had a different kind of flaw. For my Basic Math, Pre_Algebra, and Algebra classes, I had several books of "self_checking" worksheets. These worksheets had puns or puzzle questions at the top, and as the students worked the problems they were given some kind of code for choosing a letter to match that answer. If they worked the problems correctly, the letters eventually answered the pun or riddle. Students enjoyed these worksheets, but there are a couple problem areas even with these worksheets. Some students would get the answer to the riddle early and then work backward from letter to problem answer, so they weren't learning or practicing anything.
Multiplication worksheets are a quick and easy way to introduce some math revision at home. At first your kids may not appreciate being given extra "homework", but the advantages they will gain from "sharpening the saw" and practicing their math will serve them well; both back in the classroom and on in to later life. With a basic knowledge of Microsoft Excel or Word you can easily make your own math worksheets, but not everyone has that knowledge so it's fortunate that there are many websites dedicated to providing free printable resources, usually in PDF format. You just download, and print _ the only software required is the free Adobe PDF reader.