It depends.
Most any PE exercise can be adapted to put more or less stress on the skin. Some are more naturally stressful than others. Hanging probably takes first prize.
Newbie hangers initially need to stretch enough skin to create some working room. Once that has been accomplished the hanger can be positioned so the stress is primarily on the internal structures. Or, if you prefer, you can continue to allow the skin to take some of the load and it will continue to grow. The BTC position generally requires more “working skin” than other positions, though depending on hanger attachment skin can be stretched in any hanging position. I’ve grown more skin from hanging than any other PE technique.
The amount of skin jelqing produces is also adjustable. Dry jelqing stretched mine until I could jelq the whole shaft using a single stroke. I’m trying to minimize further skin growth now, so I try to stay within my “working room.” If I wanted more I could adjust my technique to stress it again.
Stretching by grasping right behind the head gives me the least skin stretch, but it would be easy to move the grip back slightly to also get some skin stretch.
Pumping can also grow skin. Again, the degree also depends on the technique used. Short, low-vacuum sets haven’t noticeably affected mine.