What’s a good time to set a turbotimer? some people told me to set it for 30sec, some 1minute.
I’ve heard that you don’t really need one, as long as when you park your car, just let it idle for a couple minutes, it’s practically the same idea. Sorry I don’t have an exact answer for your question, though 
1 minute is enough, you can set it to 2 or 3 minutes for extra precaution. Yes you can idle your car instead of a turbo timer, but its a hassle waiting in your car every time you need to turn it off.
This is true. 
It’s a pain in the butt just sitting in the car for a minute, I set my tt for a minute and when I drive the car hard I just set it for 2 minutes.
i will set it at 3 min, no oil cook for me, on those srt4 factory recommends 5 min