I'm the opposite, so just as bad. I don't put my name down because I never really know because of arrangements with the kids whether I can make it or not. The Rock n Bike was a bit of a last minute fluke because I was moaning all year that I wanted to go but couldn't.
I think XK has the best idea, that way we'll know for sure they are not going to the next one their name is down for
I understand the wanting to go and hoping to get there scenario though, just remember to remove yourself if you find out closer to the date that you can't make it because of transport/illness or whatever.
It may be that certain singles put their names down which encourages others to go because they are keen to meet someone in person - that's really not fair when the person doesn't turn up.