I'm in an organization that uses this method, and I don't think it helps. I believe our "optimistic" metric is supposed to be something like "We have a 10% chan

I'm in an organization that uses this method, and I don't think it helps. I believe our "optimistic" metric is supposed to be something like "We have a 10% chance of hitting this goal," our "realistic" metric is supposed to be something like "We have a 50% chance of hitting this goal" and our pessimistic is "We have a 90% chance of hitting it". (Or something like that. I don't remember the exact values off the top of my head.) But what happens is the engineers estimate what they think it will take, claim that's the "realistic" option, then add or subtract some percentage from that for the pessimistic and optimistic values. Nobody really understands how (or if) it's supposed to work, so the estimates are still bad.