@paul_hennessy, what a great question, mostly I would say no you don’t get a day off.
Looking back over more than 4 years of it honestly I have had a handful. They are so rare that I noticed and appreciated them. They came between relapses and also after a treatment day, e.g the day after my first Tysabri infusion I felt normal. To others I look the same anyway which is very irritating. Do look out for them as you will get some…but you have to notice them when they come along.