Date Buffers are tied to event creating and editing. They are not tied to specific locations and resources. You can apply a date buffer to particular security groups within the Groups Admin Tool.

Groups Admin > Choose Security Group(s) > Configure > Event Form Presentation > Event Restrictions > Setting #5 

You can put in a revolving date buffer or a specific date. This limits how early or how late a user can create or edit an event.

With using assignment windows, it limits permissions on specific location and resources. For example, if a user has the ability to “request” a location and you wanted to limit that as the event gets closer, you can create an assignment window that could make the location “non-requestable” as the event get closer. This would force the user to contact the approver to make a change within a certain window of the event.

Groups Admin > Choose Security Group(s) > Configure > Location or Resource Security > Choose Locations/Resources you want to add an assignment window > Edit Assignment Window

In the example below, the three selected rooms cannot be requested meaning they cannot edit the rooms for their event withing 3 days of event.  If the group has "Assign" permissions, then you could add an assignment window where they could only "request" withing 3 days of the event.