I once did a refresher course where the total number of course members was one - me!
Needless to say, during the groundschool phase the "pause" in the instructors "pose, pause, pounce" technique was somewhat wasted! You also feel pretty small when you have got the last three questions in a row wrong, fortunately the instructors were normally kind enough to throw in an easy one at that stage.
The flying phase was a lot better, I teamed up with the refresher course in front of me, so now there were two of us...
