Presumably people have up to a day or two before the game to cancel. I wonder whether people generally cancel straight after the draw, or leave it to the last moment?
Pre-registration will obviously favour those who, without it, would have fallen just outside of tier 1. I think that I’m in favour, as without pre-registration those who were just outside of tier 1 would have been part of the tier 2 bun fight, albeit that there would be more tier 2 tickets...