I bought your book "Great Application Essays for Business School", I find it highly useful for brainstorming and finding the right material for applications (especially for Wharton's app essays).
On the "failure essay" section, you listed one of the "don'ts" as writing about a failure that is more than 5 years old (P. 99).
Failure Essays: What Not to Do
5. Choose a failure that's more than five years old or whose subject matter is otherwise inappropriate...
I have the "perfect failure" which fits perfectly with all the other criterion you set. Its not inappropriate (professionally related), not at all trivial, its a true failure for which I am personally at fault (well... 99% at fault), I consider it my biggest failure to date, I drew plenty of positive lessons from it, and I matured a bit more as a result. I cannot think of a more perfect story for the Wharton "failure essay". The problem is - it happened about 8 years ago.
In this case, would it be okay to use this particular story even though you consider it "too old"? Or do I have to simply dig deeper & find a more recent example, even if nothing else compares to this one in terms of seriousness or positive impact?
By the way, a shout out to all those who are in the process of writing/editing essays, check out Paul's book, its a great resource, especially on what not to do.