One of the fascinating characteristics of Tableau as a software product is the ability to discover ways of mixing content and functions that are not by the book. You can stumble on to something serendipitous by thinking “I wonder what will happen if I do this”. Worse case, it doesn’t work. Tableau is forgiving with its infinite back button. Best case, you find a Tableau trick which will open up new features to your visualizations or save you a lot of build time. I think of Tableau as having “plastic programming”. How you use it is very malleable versus rigid and inflexible.
A case in point related to importing a workbook as a data source. Sounds like a non sequitur, but on the data connection menu if you go to Connect > Other Files the default selection shows *twb workbook files as an option. So I wondered what would happen if I did this. Found out it doesn’t gain you anything as far as an additional data connection per se. But it pulls in all your dimension and measure fields, groups, calculations etc. you created with data connections from that other workbook into a fresh workbook without having to edit out worksheets and dashboards from that prior workbook file to start over. A big time saver.
So be inquisitive and experiment with Tableau.