GTL tracks usually have built in detection systems that will send a message if you are too "optimistic" with your driving line, particularly at chicanes and sharp bends etc.
You are generally allowed two cut warnings before you get the dreaded third cut warning and an automatic Stop and Go penalty. Failing to take your S&G within one lap will result in a DQ.
Often all further cut warnings after your S&G will result in further Stop & Go penalties too, so be carefull.
A Stop and Go should be treated just like a Pit stop but no work can be carried out on your car so when you stop at your crew chief, hit return when the pit board displays. The timer will now commence. Your Crew chief will signal when your penalty has finished and then you can leave the pits, again following the same procedure as for a normal pit stop.
To remind yourself about Pit stops read
this
