I logged this in Tracker (MDL-41037). I'd be interested to hear whether others think something like this would be worthwhile pursuing. If you do, say so and vote.
A requirement for a site I am involved in building is that a particular course is available to corporate clients who will send a group to monthly workshops where they will work through one topic. That topic and past ones are to be available to them with future topics hidden or greyed out until the next workshop. Here restrictions are based on dates of the workshops with a certificate to be issued on completion of assessment tasks which are not date-related. There could be several such groups going through the course at different stages which poses a problem with the date-based access restriction. Individuals, too, can enrol for this course - their restrictions will be completion of a topic's assessment tasks to a satisfactory level before seeing the next topic. Currently the only path forward for me is to carry multiple copies of topics or whole courses. My suggestion: Similar to the current menu structure. When a grouping is selected, all the access restrictions are then displayed for that grouping. Another grouping in the same activity, topic or course could have a different set of restrictions. In this way several groupings use date restrictions and roll through the course at different times and a grouping of individuals could work through at their own pace. So the access restrictions are subordinate to the selected grouping (or no grouping, for that matter).