All of those green ground wires should be "home runs." IE - wires that run directly to the box, and then that box connection runs directly to the main ground wire.
Lando can correct me if I'm wrong but I think he means there should be no splicing of ground wires. The wire should run from its source uninterrupted to the grounding post. I think if you look through hunter's build thread there are some really good pix of how he did it.
Just run all of the ground wires to the bolt on the box. That's all you have to do. You don't want that wire nut coming loose and then only part of the circuits being grounded. No, it's not likely to happen, but why bother taking the chance?