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Hey, Dave here from the Help Team! This is really up to you and how you want to organize your campaigns, however I think you are right about not overly complicating it.  I would suggest that you track your entire domain in one campaign and categorize your keywords with labels.  If you decide to later track specific sections of you site, you can, but its probably good to have one campaign with an overall view of your entire site.  Hopefully that helps!