Hi Hanniball.
I have been using Jes Extender for more than 3 months, and I must caution you to take it slow, although you say you are “free” to use it as much as you want. The point is, that after you have done the first period of 4 weeks, you should just start over again - but this time with a higher traction than what you used in the previous period. This is to getting your penis accustomed to the traction. I hope that you have started out easy and not been using more than 900 grams of traction. Next 4 weeks, then use 1200 grams and 1500 for the following 4 weeks, for as many hours that you are using it now. After those weeks, you can extend the sessions, and use the extender for up to 8 - 12 hours a day - and I recommend to start with 1200 grams for up to 8 hours or more. The use of 1500 grams for that many hours should come along later.
In a video at their website, they tell you another program to follow, as opposed to the program written in the manual that was included with the set. Check out the video for details, the program there is more moderate.
Be careful not to overdo this. It is very easy to get sore, and even get open wounds that MUST heel before you continue , should you be that unfortunate.
Any link between muscular gains and gains in your penis ? Well, I can only use myself as an example, and I have been doing sort of bodybuilding some years ago, and I had slow gains in my muscles due to low amount of those 3 types of testosterone we have in our system. ( This was later on verified by blood tests I had to do because of a health problem.) When starting PE however, I have made fantastic gains in just over 3 months. Going from BPEL 17,5cm to almost 20cm, and 0,5cm girth gain. I didn’t know anything about jelqing, kegels and other things before I visited this fabulous website, and have been doing those exercises also alongside the use of extender. I have been using the extender for an average of 5 hours a day for the first 3 months. After discovering this website, I have swapped out some extender-sessions with manual PE exercises.
Good luck with your PE and gains, and remember to take it slow. ( Swedish : simma lungt )