if you can confidently tick off every item on the checklist, do not include anything additional. they won't 'like' you more if you do. sometimes, you are unable to provide a document. only in this case should you include other documents that you think can be used as a substitute. of course, you should explain this in a cover letter.
Please refer to Item 10 > http://www.cic.gc.ca/english/pdf/kits/forms/IMM5610E.PDF
I think Pay stubs are not 'additional' documents but 'supporting' as per the list. I suggest you should go ahead and attach the Pay stubs for the entire period.
if you can confidently tick off every item on the checklist, do not include anything additional. they won't 'like' you more if you do. sometimes, you are unable to provide a document. only in this case should you include other documents that you think can be used as a substitute. of course, you should explain this in a cover letter.
I think CIC's meaning is you do not submit your working stuff. E.g., if you are a nurse you dont have to submit patient's bleeding tampons; if you are a engineer you dont need to submit your construction paper...
Pay stubs are not required documents. However, if you are paid hourly, and if the number of hours you work per week vary, then paystubs are useful supporting documents.