Everyone is a setup expert, or so most people would have you believe. If you want to be successful, then you must learn enough to make your own tuning decisions within your own team. Listening to advice from others is one thing, but putting it to use is another. Even if the person offering advice is very knowledgeable, that person likely does not know your situation, preferences, resources or needs. Most often, the person offering advice is less knowledgeable than you are, and usually only knows a couple of things that could cure your perceived problem.
Any plan is better than no plan at all.
Take the time to create a game plan for each race, beginning with your realistic objectives, maintenance schedules, testing and race strategy. Remember that part of a good game plan is the flexibility to alter the plan as needed. Usually, no plan equals no result. The driver says the car is oversteering, but the real problem is the corner-entry push. Adjusting for the oversteer will make the problem worse.