In my case I built the car (ok, bolted on suspension and changed springs, lol) to be tail happy to some extent because that's easy to dial out with a front bar. I HATED the understeer of the car on track. Sure, it's technically safer but it was impossible to go faster without driving like a total jackass to make it oversteer.
So now that I've got 5 autocross events under my belt with the car and I understand what it's doing I need to dial back the oversteer. I can't drive the car hard because I have to be a bit gentle to keep the rear from stepping out. I'm still at the limit currently, but the limit is the rear tires, not all four. Ideal balance is all four tires starting to slide at the same time.
Set up the car however it makes you comfortable. I love how my car feels right now, but it's limiting my times and I'd like to catch the local hotshoes. I drove pretty well at the last event and paxed 16th with a lot of VERY good drivers, but I did some side by side comparisons and you can see how much more aggressive they can be with the car. For example (two different classes of car I know, but I should in theory have only been 2 tenths off to PAX the same, and he's a trophy winning driver & car): [ame="https://www.youtube.com/watch?v=QDxbR_sIN68"]04 16 2016 Phila KenVsJon (STX vs STR) - YouTube[/ame]
I think the idea of matching car to driver skill has some merit, but I've always felt that I should be able to drive a pro level car and if I can't, what am I doing wrong? That said, there's certain skills that really high level drivers that take time to learn. Trying to drive a setup that works for those skills when you don't have those skills is a big exercise in frustration