I am confused about the queues for the Worlds.
Why is it that sometimes a queue appears when the world is full and MOST of the time, a message appears saying World is full and try again.

It would have been fine if a queue appears all the time when the world is full, then we would just wait for our turn. But when there is no queue, we would just keep clicking and trying and trying which is way more annoying.

So what is the normal behaviour, having a queue or not?