I have a 987.2 Cayman R and like Andy said, you can’t turn off PSM entirely, short of installing a kill switch. It’s always partially on in the background for when you really mess up (although I’ve still spun the car playing around at Cayuga). If you lock up both front wheels in Sport Mode (activate ABS) or one wheel without Sport Mode, it will fully re-engage. That said, from the day I bought the car, I always turn it “off” in the dry. The cars can brake the rear wheels (Automatic Braking Differential) as a way of limiting wheel spin, and it will add extra wear to the pads and rotors. My friend literally cooked a set of rear brakes on a GTR leaving stability control on at Mosport.
If you have Sport Mode, it will let the car know that you want PSM to intervene less, but in general the car doesn’t know you are tracking it and probably want it to do things that it doesn’t expect to do on the street.
In other cars, I have specifically felt the stability control cut power going through turn 2. I guess it didn’t like the slip angle. But the last thing you ever want to do is lift in a turn. If I did have to lift anywhere, I’m pretty sure I’d want to straighten the wheel out first and PSM isn’t going to do that for you. In most places, if things are going wrong, more power is going to help more than less power.
If my rear tires are starting to slip under power going around a corner, I’d rather keep my foot on the power and counter steer a bit than have the car cut power and brake individual wheels trying to bring the car “back under control”. Especially if you have a car on your back bumper who wasn’t expecting you to brake mid corner!
I don’t think it’s about going as fast as you can, but it is about learning to control your car better. If the computer is constantly cutting in, you’re either asking the car to do things that it can’t, or it doesn’t understand what you are trying to do.
It’s easy to mash your foot to the floor and let the computer figure it out, but it’s much more rewarding to learn how much throttle you can apply and how quickly you can lay into it.
I wouldn’t go out in Green will all the aids turned off, but maybe try to turn them off and play around in a parking lot? Maybe once you have the racing line, gear shifts, and entry speeds down to the point that you don’t have to actively think about what you are doing and are laying down consistent smooth laps, it’s time to try turning it off (and take it easier to start with, and work your way back up). Obviously if you are finding that PSM is actually holding you back from reaching your potential, then you know it’s time to turn it off.