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.
Mathematics skills can improve with just one technique _practice! Most of the children end up petrified of numbers and number games because of lack of appropriate knowledge. All this is a result of poor teaching mechanics. The vast school curriculum does not teach the children the perfect way of learning the subject. It's only proper practice and regularity that can make a student reach perfection! Do worksheets help a child?