"2 weeks" may mean the last two calendar weeks, the last and the current calendar week, or the last 14 days. Without even going in to the ambiguity of what a ca

"2 weeks" may mean the last two calendar weeks, the last and the current calendar week, or the last 14 days. Without even going in to the ambiguity of what a calendar week is (a calender week starts on a Monday, and I will take no opposition), 14 days is less ambiguous (and therefor better) than two weeks. The same goes for the other ones.