How do I know whether AI planning is helping me?
Judge a planning workflow by what you finish. In Tyra Banks's personal planning example, the part that stood out was her saying she was doing the suggested activities, and I'd hold any AI assistant to that same test. A list and a completed plan are different results.
If your assistant gives you more options than you want to read, narrow the assignment. Ask for one plan that fits a specific free period, plus one alternative, and have it include what you need to decide: the location, the timing and a cost to verify.
Then notice where your follow-through stops. Maybe the suggestions run past your budget. Maybe they depend on travel time you don't have, or your calendar was already full and you got ideas anyway. Each of those is a correction to the brief.
I wouldn't hand the AI the job of deciding what matters to you. Tell it what kind of time you want to protect and keep the choice yourself. After a week, look back at whether you chose and finished anything you valued. If all you got was a longer reading list, change the output.