When can a multiple bronzium pack slider be created?

Another similar game found a way to open multiple packs at once.
They started with allowing players to open 10 at once.
Then, very recently, the game allowed as many packs as you have. The game will open 10 at once for you every few seconds until you tell the game to stop or your run out.

I had over 400 at one point and did bother to open them as it would take too long.