I routinely shoot between 80# and 100#. But, I also have a 120# Longbow. As a dyed-in-the-wool heavy bow shooter, I can tell you a little of what I know.
All of my long bows that are, long, ( 66” to 72”) draw smoother and easier out to my full draw. They don’t stack.
I recently “attempted” to shoot a 62” 112# at 28” Recurve. I got it about 20” before I ran smack dab into a “Stacking Wall”. From there, I only got 2 more inches of draw. I was well short of my 27 ½” draw length.
Here is my reasoning as to why;
The longer the bow, the longer the draw before stacking, thus allowing me to get more back muscle into the draw. With the shorter bow, the draw weight increased dramatically before I was able to recruit my back muscles. Essentially, I was drawing with only arm strength, not back strength.
The Posterior Deltoid (unless you are Marlon Torres) is not designed to draw that much weight. The Medial and Posterior Deltoids begin the draw but the Latissimus Dorsi starts to take over the load quickly, followed by the Trapezius. Eventually the Longissimus Dorsi are recruited. (i.e. the elusive “Back Tension Muscles”)
Okay, that’s my explanation.
Matt