Win-win strategies also involve the feelings of either party. In the example quoted above, the project manager readily agreeing to an offer of $17,000 might make the software vendor feel he has quoted too low, and the vendor readily agreeing for $15,000 might make the project manager regret not having quoted $14,000. They walk away feeling as if they have not won.
Even though a deal is good to you, you should take some time before submitting your answer. For example, consider a worker negotiating wage and working conditions. A project manager readily conceding trade union demands for wage increase or for reduced working hours to mitigate stress creates an impression of the workers getting a raw deal.
The project manager allowing for the same after much deliberation, analysis, and study creates the impression of a fair deal. Similarly, the project manager agreeing to a perfect proposal of project deliverables without any comments might lead to project owners developing an impression that the timelines are too light, causing them to push for additional work or bring forward the deliverables.