Good questions Manzwa,
I started off wearing mine with 3 lines still showing, then just 2 lines but I found it very uncomfortable to wear for anything over 45 minutes at a time. I completed 150 hours like this but my penis retracted as soon as I took the PM off.
Then I reduced the amount of rods I used and wore it at low tension so 4 lines are showing. This stretched my penis to about 80% of my NBPFSL. This was still 20% longer than my FL.
Now I can wear it for a couple of hours at a time with more comfort.
Whether or not I will gain from this only time will tell.