When enriching your date data, week information is pretty critical, I suggest adding %w to the format stings as well..
Several month based expressions can also be made weekly, data time first of week #31, last of week #45 etc....
Also came across a lot of questions at our community on how to turn week based data...
Writing the formula is obvious (Ceil(DateTimeDiff([Today],[Date],'days')/7))
but having a DateTimeDiff([Today],[Date],'weeks') is preferable don't you think?
Cheers