Somewhere during the check ride personal minimums will come up. Interestingly some people have never thought about them. Some make them up on the spot. Others will tell me something but we actually go fly the check ride busting those minimums they've established.
For example, we'll be talking about the weather and I'll ask what would be the lowest ceiling and visibility they would fly this cross country on. I'll hear "Oh, I've never thought about it, clear skies and say no less that 15 miles?" and yet we take off on the check ride with the ceiling at 2500 feet and vis at 3-4 miles. I'll ask about winds. "I don't fly with winds gusting over 15 knots and no more than a 7-8 knot crosswind" but yet we launch on the check ride with winds gusting to 25.
Fuel minimums: Almost everyone tell me they double the FAA requirements for fuel reserve. But you know what the number one reason engine failure is? Fuel starvation and/or fuel mismanagement. Do know how close to the destination they get before they run out of fuel? Within 5 miles. This tells me we don't really follow our personal minimums or we don't know how to correctly plan a cross country and/or operate our fuel system.
Personal Minimum keep us within our skill set, they keep us safe. Personal Minimums can change as you build knowledge, skill and experience. They can change up or down for different situations. For example, you just got checked out in a new airplane and you're not as comfortable with cross winds as your old airplane. You're flying a cross country at night. Will your weather and fuel mins be the same as during the day? Maybe you got that new instrument rating. Should you launch off when the weather is 200x1/2. Remember just because it's legal doesn't mean it's safe.