"Air Traffic Control" for campaigns is very tough subject and cannot be perfect. Keep in mind the more complex the rules, the slower is the delivery prep since Typology rules/Pressure rules will applied at the time of delivery activity node execution.
Having said that, you can always calculate the Monday of the week using expression and they use Today - Monday of the week date to calculate # of communications/messages sent to a customer and use that in the pressure rule. Assuming here the week is Mon-Sun. Similar approach of your week is Sun-Sat (calculate Sunday date of the current week).
Of course things can get complex if you want the rule to apply to certain type of campaigns/communications but not all of them (back to my first statement above).