So here is the use case.  Lets say your corporate font just got changed from Arial to Segoe UI.  Or, you are just plain tired of having to format your Quick Filters, turn on and off your those pesky tooltip buttons, or want all your field labels to always be hot pink with glitter.  I am still waiting for the glitter feature in Tableau by the way.... hint hint.  You could spend a day changing  your workbooks, yawn!  If you are lucky you have a corporate Sugar Daddy who will buy you Power Tools, an amazing product, do that.  But if not, you can get similar results from DIY Find and Replace in your favorite text editor.  I use Notepad ++ on a PC or Sublime Text on a Mac