Although I've been doing SS for a few months, I've only just recently read the book. In the programming chapter, rip mentions that no workouts should be missed. I typically end up missing about a workout every 5 or so weeks. Does everybody else get every single workout always?
Coincidentally, I'm geting my wisdom teeth removed tomorrow, and as a result will probably miss Friday's workout. The last missed workout was May 2nd.
Stuff happens. The point is to make the training a priority and learn to schedule other committments around it. Medical issues, work and family emergencies will sometimes take priority over a training session. If it becomes habit then you may have to look at how you are organizing your time.