I have been thinking about this a lot over the past months, most teams and projects fail because people get in over their head by
* Not analyzing the problem deeply enough (hrs not weeks)
* Estimating too early, they don't want to look weak
* Not revising estimates once they are in it (heroic save)
* Not asking for help or re-analysis from outside minds
As a poster above mentioned, accepting a bullshit answer is being complicit in a lie. We need to push back in a polite way when we are being bullshitted. By accepting poor estimates (in all the dimensions of poor) we enable failure.