Is it possible to have more than one challenge at the same time?

A user can only have simultaneously one administrator-assigned challenge directed at them, one public challenge, one monthly personal challenge, and one daily personal challenge.

Additionally, there can only be one active public challenge at any given time for the entire platform.

Therefore, at any given time, a user can participate in up to 4 challenges: the public challenge in which all platform users participate, the challenge that the administrator has assigned to them as a directed challenge, and the two personal challenges created by themselves.