Thanks Sam for answering this question! My hair was on fire trying to find a solution. I know this was quite a while ago. Have you heard anything from Power BI about addressing this issue? I feel like this is a very awkward workaround for a fairly standard problem. I deal with a lot of Walmart data which is a fairly large company and the bulk of sales data is stored at a week level. Surprises me that DAX hasn’t changed to help out a broader audience dealing with week level data.
At this stage I don’t believe there is any other built-in workarounds for weekly data in the DAX language. I would presume there isn’t because there’s so much variability in terms of weekly timeframes or weekly calendars that businesses might use. Whereas a standard calendar is uniform across everyone.
It does take a little bit more from a formula perspective but it’s also a very good learning experience because you have to form a good understanding of how FILTER works and how you can manipulate the context of a calculation using this function