A great conversation that changes nothing is a nice chat. Founders have very little time, and every hour they spend with a mentor is an hour not spent building or selling. That hour should move something forward.
Before the conversation ends, make sure both of you can say what comes next: a decision that's now clearer, an action with an owner and a date, or an experiment with a defined success criterion. If nothing concrete comes out, ask why, and whether the conversation was the right one to have.
Specific beats general. “Talk to more customers” is advice. “Call these five logistics managers by Friday and ask how they handle returns today” is a next step.