I have said it before and I will say it again, the best line in every proposal I have ever written is, “Any change in scope will affect timing and cost.”
In the hundreds of projects I have done, there was only one where the change in scope as dictated by the client decreased the amount of time and lowered the cost of the project. There were several times that our recommendations decreased time and cost after we got customer input. Every other change in scope, the vast vast majority, increased cost and timing.
But I follow that the customer is always right. I don’t care if they take my recommendations or not. It is not my project and not my money, I have nothing vested. It is a business relationship, not a friendship. They are not obligated to like my ideas and I am not obligated to purchase their product.
And I always loved it when they wanted changes. Because of that line above, it meant more work and more money for me. What’s not to love?