As an instructor I’m gonna disagree with the understeer approach. The most effective way to slow your car is with the brakes and 0 or minimal tire slippage. Understeering will compromise your braking and your turn in (kinetic vs, static friction) and will very quickly overheat your tires which will further compromise braking and effect handling.
Here's a helpful way to think about drip. The amount of grip is represented the outside of the circle (the adhesion limit). You can use this grip for accelerating, turning or braking. If you are turning and braking, or turning and accelerating the amount of grip you have will be split between these two functions. For a turn at the end of the straight away you want to start with all your grip being invested into the braking (which means your wheels will be as straight as possible), if your wheel is turned at all you'll be using some grip for turning. As you enter the turn you'll start to lift off the brake and turn in, your tires will still be at the adhesion limit but you'll slowly give more and more grip to turning and less to braking (this is called trail braking). As you accelerate out its the exact opposite, you'll invest more and more drip to accelerating and less to turning as you open up the wheel out of the corner.
If your tires slides at all this adhesion limit (or circle) becomes smaller and smaller and you have less grip to use for braking, accelerating and turning.
