You do not need to agree with me. You do need to be willing to examine the reasoning.
The relationship tends to work best when the problem is genuinely unresolved and the person bringing it is prepared to examine the answer rather than defend a predetermined one. I am considerably more useful when candor is valued over reassurance, disagreement can be considered without being interpreted as disloyalty and improving the decision matters more than preserving the appearance that the original instinct was correct.
If the problem is difficult, unresolved, expensive, consequential or unusual enough that conventional advice has stopped being useful, I am interested in hearing about it.
If I am not useful to the situation, I will say so. If I am, the next step generally becomes apparent from the problem itself.