I totally agree. I tend to phrase it a bit differently: "If you need to know how long it will take before deciding if it is important enough, then it is likely

I totally agree. I tend to phrase it a bit differently: "If you need to know how long it will take before deciding if it is important enough, then it is likely not important enough." Another kind of corollary: "If the business will go under if we don't get this done by X, then we probably need a new business plan, not faster development". These are rules of thumb and there are definite places where they don't hold, but I've found it genuinely useful to consider when the inevitable tough questions start to get asked.