Once airborne you are only required to calculate and verify that you can stop within 100% of the available runway, the other figures quoted are for dispatching purposes.
As with any decision process, consider
(a) if the situation is a real emergency and action is required right NOW, then one needs to know where the worst case boundary fence is located and do the best one can ... ie what is the 100 percent figure and one expects to overrun the end a little ...
(b) if one has an emergency but resolution is not required right NOW, and there are several options available to the resolution process ... would it not be sensible to consider the certification requirements .. ie, in this case, if one had the choice of, say, three runways to recover to .. then one might prefer one of the runways which had the certification factor available ... just one less argument to face at the enquiry .. ?