I had to make a decision quickly when the Mass ran long and a short third hour was pared to ten minutes to review for a test the next day. Reschedule the class? Postpone the test? I decided to go over the most essential material in that time and to offer a review session that evening through chat on Moodle.
It's not a decision made lightly, although a couple of other teachers in our school have done this. I already have been questioned about whether I need to be as available to my students as I am through e-mail. But it seemed like special circumstances. I only had about three or four students take me up on the offer, but it's a good thing we straightened out confusion about the "blinding of Isaac!"