I think most of us have been in position #4.
The main thing that I'm trying to do when in that position is to explain as much as possible all the counter-arguments, in the simplest way possible.
However, there are cases in which it's normal to understand why you need to cut corners, especially if you're trying to build an MVP.
That being said, since I'm always trying to do my due diligence on explaining all the possible outcomes, if everything comes falling down, I don't feel accountable at all, nor do I make my co-workers feel accountable in relation to the project/client if all the red flags were rose beforehand.
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