There are many math_based games available in educational toy stores that will help to reinforce the principles your child learns in worksheets. Computer games can help too, but depending on the age of your child, it is best not to encourage too much computer use at an early age. Everyday activities can be turned into math lessons too. A trip to the grocery store can turn into a math lesson if you encourage your child to help you count how many items you are buying, or add up the bottles of milk as you add them to your cart.
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.