Is this normal?
Random thoughts that distracted me for a few controls

- the act of punching dislodges a significant proportion of cards?
- people keep them to show at the start, and then dispose of them?
(but being 'responsible' throw them where they think someone will collect them later!)
- someone lost one accidentally, but then other people deliberately discarded at the same place rather than risk littering elsewhere on the course?
- there was a batch of slightly undersized cards at that event?