Would be difficult to add recurring cycles like in Microsoft Outlook? For example, you could set a block, have it recur for whatever period and put an expiration date? I work shift work and it's always four days working, four days off.
It would be much easier to add a recurring block and check off repeat until whatever date. Monday, Tuesday, Wednesday, Thursday blocked > Repeat every 8 days so that the next week Tuesday, Wednesday, Thursday, Friday would be blocked and so on.