Fine, most of these activities would have doused during the weekend due to the official closure of the service of the companies. However, since Bitcoin is an electronic means of payment that doesn't regard the weekend, companies may decide at some weekends to process customer's withdrawals on both Saturdays and Sundays, while customers too may decide to send in a deposit on those days. And at some weekends, this could become much more comparable to that of the weekdays if the activities are much, which could influence an upward fee on that weekend.
If this is again coupled with a high number of Unconfirmed transactions, much reduction may not be seen in the transaction fees on that weekend. That's if we'll see any reasonable reduction at all.