I came to understand how to use the fail-safe. I thought I had every answer in my mind. As I went to write this page down the first time, I realized while I was writing on the topic of how Aaron should have used the fail-safe, that it was exactly what Aaron did.
Originally, Abe teaches Aaron that you must leave the box running whenever you exit from it, as you are inside the box traveling backwards. While well-intentioned, it is incorrect.
You can leave it on and wait for your former self to get in the box and disappear. But, you can overwrite this part without creating a paradox. This means that, you can skip this part completely. As you exit the box, you are in a new timeline. It does not matter if you leave the box running as you are not in the box. Your travel has created a new timeline that overlaps the original timeline. It would be best to leave the box turned off until the time has past where you entered it in the former timeline. Since you are in a new timeline, turning the box off will prevent anyone else from entering that timeline, which could even be yourself. Thus, Aaron(3) can prevent Aaron(4) from entering the timeline by turning the box off after he exits. Aaron(2) does not do this at first, until he confronts Aaron(3). He then considers how to prevent future selves from interfering with his plans.
Abe(2) learns this step when Aaron(2) tells him that he was confronted by Aaron(3). Then, he will travel back to both drug Abe(1) and prevent any future Abe’s. When any future version steps out of the box, they start writing a new timeline. Besides, every time you leave your time machine on, it seems to create a disaster where time travel becomes necessary. So the machine appears to always lead to havoc.
As a side note on having a running fail-safe, it becomes useless to have it running for any length of time that is more than can be endured. If it is only large enough for four days worth of oxygen and water, then it becomes useless after four days and must be reset again. The only other option is to build a much larger box, one where more food, oxygen, and hopefully a toilet, can be placed within the box
