I would suggest a slightly different framework. Never say "turn back now." However, I try to divide my criticism into three groups: 1. Major show-stoppers n

I would suggest a slightly different framework. Never say "turn back now." However, I try to divide my criticism into three groups: 1. Major show-stoppers need to be discussed and brought to light early on. The point is not to say "don't get started" but rather to say "do you have any idea what you are up against?" Having an idea is the first step to planning, and planning is mostly valuable for mapping out obstacles and potential solutions. 2. Once one is past the commitment and planning phase, I think it is fine to criticize implementation. The goal here is to bring up problems that might not need to be solved right away but need to be on the radar. 3. These need to be coupled with constructive support. Heavy criticism along with solid support is golden. Heavy criticism without solid support is like a lead weight.