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.
It is amazing the difference in effort you will get from worksheet to worksheet. Granted the amount of effort may vary immensely from year to year depending on the group of students you have. However for the most part, when a worksheet is needed to help drill down a procedure, standard, or lesson, its effectiveness can and will vary. Therefore it is our job as the teacher to make sure that when we need to utilize a worksheet, we provide the students with one that is as inspiring as can be. Times are different these days. Kids are growing up in a world of microwaves, fast food chains, Nintendo, Wifi, iPads, along with a ton of other technical marvels. When I was growing up we didn't have home computers let alone PlayStation to entertain ourselves. Handheld camcorders were barely coming to the retail market by the time I was in 8th grade, but still a long ways away from the YouTube and Facebook arena we now see today. Times were extremely different back then and so was school.