Another problem with almost all worksheets is that they don't prevent incorrect answers. Self_checking worksheets just let the student know they did something wrong__after the fact. I am a firm believer in the concept that, if at all possible, learning should be structured in small chunks in such a way that there is very little possibility for error. Worksheets often allow for mistakes to be made and then to be repeated many times. A mistake that gets practiced is extremely difficult to correct. This especially happens when worksheets are used as time fillers or baby sitters and the work isn't really being supervised.
Now that we know the benefits of mathematics what is needed to conquer this hard to tackle and arduous subject. Answer is quite simple actually, practice, a lot of practice from early childhood. But in order to perform any task or practice any task, one requires resources. Obtaining a resource is not difficult in today's modern world but affordable resource is definitely a rare commodity. Today education is a sector which gets very little funding from the federal government.