The bundled stretches are not for beginners, that's for sure. I do them almost every evening, twisting my dick three times around and then pulling from both ends while twisting and pulling in reverse directions. I can get an extra three inches out of my flaccid stretch (straight up) when I kegel after doing about two or three reps of a half minute each of these.
But I didn't try the bundled stretch until I had been practicing p.e. for a couple of years. This is my 6th year now.
So be very careful with them. My cock is super-conditioned. This is why I can practice these without injury.