You're welcome.

Think of it this way: If you go lean against a fence post with just your arm supporting your body weight, and you've got a pretty good bend in it (as you did in that pic you showed), how long do you think you can hold yourself up as opposed to it being straighter with more bone-on-bone contact?

Obviously, I'm not talking about having it hyperextended and locked out, but rather how it would be if allowed to hang naturally at your side.

Going hand-in-hand with this is using a proper grip, which means the grip of the bow should sit on the pad of your thumb and not in the palm; workk on having your knuckles fall off at a 45-degree angle from your bow riser.

Lastly, make sure you work on having that front shoulder bottomed out. It will feel very weird at first if you're not, but ultimately will allow solid bone-on-bone contact all the way through from your bow riser to your torso, allowing the most solid, repeatable and fatigue-free platform from which to shoot.