@Tom_Galland, you might be saying one of two things:
a) you want the app to show the data grouped by Department name -> Day of week. I think this is what Aleksi assumes you meant. If so, you can use the grouping option in the Table view to achieve this b) you have data sitting in different sheets by day of the week and department. you want the app to aggregate and show all these different sheets as though they were one sheet. I suspect this is what you mean. If so, this is not a suitable data representation for AppSheet. The system does not union/aggregate a large number of distinct sheets and treat them like a single set of data. I would advocate merging all of these into a single sheet with extra columns for Department name and Day.