It's the situation everyone fears, you've spent all week looking forward and getting ready for D&D and someone cancels. You don't want them to miss out on the cool plot points you've planned out, so do you cancel?
It's the situation everyone fears, you've spent all week looking forward and getting ready for D&D and someone cancels. Your carefully planned and balanced session was designed for 5 players and now you've got 4 (or less), and maybe even the person missing was important to the next part of the story.