The Guide mentions to you in the game that he actually uses Locke, Rahel, Smiley and Ezrebeth as test subjects to make sure the items work. Now that he knows that they do, it's definitely better for Astrid to maybe be smart about it and not drain everyone instantly since that will probably make "God" suspicious. At the same time, Astrid and The Guide really can't afford to wait for everyone to just be ready to leave, especially if they take a long time to do so. They're definitely in for a challenge there in how they're going to tackle their little plan. :)
"The box" is a state that The Guide puts people in so that they can't do anything, which is why he calls it a box (even though it isn't literally a box). I like to think that he puts them somewhere in the void. He did that in the solo route to force everyone to help Astrid, and basically to show that he can be a real douche when he wants/needs to.
You're so welcome! :) And thank you so much, I really appreciate that! We put a lot of work into the game and it means so much that people like you enjoy it and ask about it. <3