@pdf23ds

Working with a small team on impossible problem takes extraordinary effort no more than it takes a quadrillion dollars. It's not the reason to work efficiently -- you don't run faster to arrive five years earlier, you run faster to arrive at all.

I don't think you can place lower bounds either. At each stage, problem is impossible because there are confusions in the way. When they clear up, you have either a solution, or further confusions, and there is no way to tell in advance.