Do you agree that only the activities made after joining a challenge should count for that challenge?
It's not the first time that, almost in the end of a challenge, some guy accepts the invitation and spoils all the fun. Suddenly a guy appears as a leader from nowhere.
I think it spoils the concept of a challenge. The ideia of a challenge is to fuel a nice competition along the duration of the challenge. Not that somebody appears in the last day and "steals" the thing. Don't you agree?
I think that only activities made after joining a challenge should count for that challenge. Otherwise it's bizarre and spoils the purpose.