In particular for software, instead of gaussians we often have the sort of distribution of completion times where "if the expected completion time is T1, but em

In particular for software, instead of gaussians we often have the sort of distribution of completion times where "if the expected completion time is T1, but empirical observation says it never actually got done in between (0,T1], the conditional expected completion time is T2, and T2>>T1": ie, the longer you work on something without success, the further away into the indefinite future the horizon of expected success recedes...