On a previous game I've played, events were always running. Each event lasted for either 3 or 4 days (there are some rare events lasting 7 days, but that's the exception to the rule). In each event, you play event levels where you get tokens to buy stuff in the event box. The tokens were considered separate for each event, and the box only lasted as long as the event lasted, so once the event has ended, all tokens you haven't spent were lost.
Near the end of the game's life, some of their screwups included:
- Running an event that gave the wrong kind of token. No one can pull anything from that box. It was fixed about a day after that.
- The ending date for another event was given the wrong year, so we had an event that would've lasted a whole year. This is well after its closure was announced (which would come in about two months after that). To many players' dismay, it was fixed within about a week after the event ended.
After those bugs, I don't think there's any bug in DS that would surprise me anymore.