In case it helps, and if I've understood requirements, below would look for most days worked back from today
Please note that reference above to $A$24 is a cell containing the following -- and is used to negate need for duplication of calc {the same could be stored in a Named Range etc}
Note: to test I had to extrapolate your sample data such that there was activity on today's date... it's also unclear what you would want to do if the answer exceeded 13 {I believe you said this could not happen and have thus ignored it, per se}
if neither solutions are doing what you want it might make sense to post a further sample, alongside expected results in each case.
Bookmarks