Open challenges get answered faster
Post an open challenge and a rival close to your strength usually takes it within a couple of minutes.
Open challenges no longer sit in the lobby for hours. Most of the time someone with a lineup close to yours picks it up within a couple of minutes: no steamrolling newcomers, no throwing the match.
If hardly anyone at your lineup's strength is around, the challenge page says so. Bring stronger cards and it will be taken sooner.