How long is a piece of string?
Follow the newbie routine for as long as you can whilst gaining results and not over-straining your unit which you can check via your physiological indicators. If all is fine except that you are not gaining, then after a few months, you should hopefully have an idea what your penis may or may not respond to. At this point it is up to you to delve into all that advice and choose a route. If however, you are still gaining on the newbie routine, then why change?
Almost everyone here proffers the advice of taking it easy when trying out a new exercise or technique for PE. In my mind this is sensible, as no matter what your positive growth targets are, the negative of an injured penis far outweighs them. So be cautious. You may find that you can do a lot to your dick and it will respond favourably. You may find that you have to do virtually very little and gains will come easily.
So what doesn’t work? Injury is my only answer. Sorry if I am repeating along the lines of what you have already read on your search through the threads. Good luck.