Ok, so when you experience the car sliding on exits, this is when Traction Control helps to avoid reaf tires overslipping. The benefits are twosome: 1) if the tires are slipping you aint going forward 😀 2) especially in high(er) speed turns, if you overslip the rears the car could start to oversteer very quickly (and the higher the speed the more difficult it is to catch it and recover).
So, basically both Sport 2 and Race have this covered. The Sport 2 Traction Control setting is a bit more conservative vs Race. Note, that if you are going too fast for a given corner and tire grip, you will either plow forward (understeer), or spin to the inside (oversteer) NO MATTER what your PTM is set as. But, anything up to and including Sport 1 will try to help you recover. With Sport 2 and Race you're on your own.
Now, folks that have tons of experience and can FEEL what the car is doing (at the 4 corners, meaning the tire grip levels), often prefer to control the car's balance themselves with throttle and steering. This makes the car turn faster, but only of the driver knows how to maintain the balance of it.
PTM up to Sport 1 will make the car a bit "tighter", meaning it will not turn as willingly, but should give ya a very safe platform. A lot of folks can make amazing laps with Sport 1. This is NOT a slow setting, but one where a computer measures the yaw (angle between what direction is your steering wheel telling the car to go vs where the car is actually going. The higher this ange (or difference) the more Stability Control system will intervene trying to reduce this angle (to prevent a spin).
So, for example, in a long, faster corner, an experienced driver would likely prefer to manage the slip angles themselves: if the car starts to understeer (go wider than the corner demands) the driver would reduce the throttle, which would move the weight more on the nose and make the car turn more. If the car started going too tight for the corner (oversteer), the driver would add throttle and hence move the weight onto the rears and hence permit the car to corner a bit wider. Of course the same applies in shorter, slower corners, but require faster corrections. Also, steering wheel corrections might be necessary, etc.
Bottom line, if you are still learning and feel that you slide the car too much (and going slower as a result, as that is always the case), then maybe stay in Sport 1 and see how it goes.
If you will feel (actually feel, not imagine 😀
that the car gets "tight" and starts to resist rotation too much, than go to Sport 2, or Race.
Hope this makes sense and hope this helps. Have fun! Cheers!