Is there a time limit for being up here? Like not the ledge boxes but the entire floor itself?

There is no time limit given when I went.

1 minute in the box for groups of 3 or less, 2 minutes in the box for 4 or more, and unlimited time on the floor.

No limit on the floor but the ledge can be 2 to 4 min depending on crowd. I spent 15 min on the ledge when crowd was very less

Yep you have 1 min inside the box and for the entire floor itself there's no time limit, I stayed around 50minutes