Answer:

First and foremost, to create an expanding Triangle, wave-e MUST be longer than wave-c. Therefore, the ONLY way that wave-e can terminate above the low of wave-c is if wave-d is longer than wave-c in price. For that reason, it is not a matter of probability, but a question of the Triangle's internal design that decides whether wave-e will "fail" or not.

If you see what you suspect is an expanding Triangle, and wave-d is longer than wave-c, the potential for an e-wave "failure" exists. That potential increases if the channeling of the Triangle slants upward. Why, that allows the "panic phase" of the Triangle (i.e., wave-e's break of the a-c channel) to occur without the need to break the low of wave-c. Keep in mind, to qualify as an expanding Triangle, wave-e MUST still be longer than wave-c in price; if not, something other than an expanding Triangle is forming.