Looking at this screenshot of date selections for the LastUpdate field in MailChimp:
You have fields like Yesterday, Today, Last Week and so forth... But does last week actually mean 'last week' or last 7 days?
Same goes for Last Month is this the Last 30 days?
If not it really would help us if the Last 7 Days, Last 14 days, Last 30 Days were made available as options?
Hope you can advise or add as a quick fix / future option?