What Roger and Terry have said here are key points: There is a threshold that each individual will operate in and in many cases, baring injuries and the like, in that threshold might be the sweet spot between bows that have enough umph to handle the tasks you'll use them for, and at the same time a bow you shoot well, a bow you may want to shoot a lot, a bow you can hold a bit if needed, a bow that is fun. I like to shoot bows in the 48 to 53 lbs area. Now I only shoot deer, turkey, have shot hogs although don't get after them regularly, small game exc ....... I also like to shoot alot at the 3D's / range targets, keeping up with form and it's obviously just a ton of fun to shoot at things. Many nights in the warmer months, I will easily shoot 100 + arrows and never stop because I'm tired or sore. This weight range does all that for me. I could shoot a lot more draw weight. Though I think regardless of training to bow up, there would come a point where I might be in that heavy range but give up a lot of what I mentioned above, and for what?!
If I were getting after a large big boned animal on a hunt that was a once in a lifetime deal on very costly hunting trip and it was necessary to drive a HEAVY arrow, I would most likely bow up if all reasoning dictated that was the logical thing to do. The heavy bow to drive the heavy arrow to have the increase energy yielding optimal penetration. I would advise to anybody who was getting after "bowing up", to do it wisely, methodically, slowly, don't push it too hardly and listen to your body. I consider my form to be at least respectable but have been told it is actually good. I'm sure I could draw bows that are in the 70's and most likely more. Would my form start to cave in after a few shots? Very high chance without a good adjustment period (training). If I pushed that even though I knew this was going on and I created an injury that would set me back, I would want to bang my head off the nearest wall. Now if I trained properly into the heavy weight, probably would be no issues. Off the top of my head, if I were to come up in weight, it would not be 5 lbs, but more in the 10 to 15 lbs increase. Though I can't see myself needing to go there anytime soon. 50 lbs will kill anything on this continent. Trajectory being a non issue.