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.
So what is the concern? There are three big concerns, actually. Our teacher "caution light" should start blinking if we are using lower_level_thinking worksheets (Example: "Check the box next to the correct answer."), if we are using too many worksheets or if we are using worksheets as classroom busy work.