Identical worksheets are needed prior to using the Consolidation feature, creating a sum across worksheets or using the Paste Special Math features to create summary worksheets. By grouping the worksheets first and then adding rows or columns, changing headings and other formatting operations, you ensure that the spreadsheets remain uniform.
As far as using worksheets for busy work, the verdict is in. It is destructive to classroom learning to assign worksheets to simply keep students occupied. Busy work creates monotony, causes boredom and increases the likelihood of behavior problems. To know if you are on the right track with worksheets in your classroom, answer (honestly) these simple questions: Do my students groan when I hand out a worksheet? (The answer should be no.) Are my lesson plans based on worksheets? (The answer should be no.) Do I feel anxiety if I don't have worksheets copied? (The answer should be no.) Are students excited about learning in my classroom? (The answer should be yes!).