I have a workspace which captures week over week and month over month numbers. How do I make sure that each week my most recent numbers are captured. Right now each week I have to go and change the selected position.
So using your calculated time periods, you could generate a table that looks like the below;
So rather than the week breakdown in your table, meaning that you need to go update the cell your summary visualisation is pointing at, you can just point your summary number vis at the visits from "this week" (calculated date period to show the last 7 days, rolling), then do your summary comparison vis showing the difference between "last week" (calculated date period to show the last 15 days to 8 days ago, rolling).
This means that each time you open this dashboard, this will update to give you the present week's data in the summary number & summary change visualisations without having to change which cell your visualisation is looking at.