Wade, I have found shouldering my gun, while still in my lap lets me make the hardest part of the move well in advance with zero fatigue. I can hold my gun shouldered and work a slate call with no problems. Using 2 hands, one arm cradles the gun to your shoulder and holds the pot (that I hand it to that hand with the free one). Then when ready, set it down, usually well in advance. Raising the barrel steadily, slowly (but faster than you think you can) and decisively is very effective. One piece of advice, make sure the sling of the gun is in the hand you are using to raise the gun. Slings have a way of catching and moving as you rise the barrel up.
I got caught that way one time as I was watching a bird across a field (hen) and the strutter came in to my hard right. The gun was shouldered, barrel still in my lap (he had gobbled 30 minutes earlier by where the hen was - or another bird did). He got wary at 6 yards, but a quick raise of the barrel and he met his maker. Even had to sit up a little to clear the briars.
Another time one came in silent, gun across my lap and me looking at the radar on my phone. He came in so close, I had to let him get out to about 15 so I felt better about the shot. Also will do a quick adjustment when he is facing away in strut. Have killed several making the last adjustment when they make the turn away from me. Cluck, head up, boom.
That was all back when I could kill turkeys. Now I just suck. man this has been a rainy, quiet year for me and my bunch. Seems like it has been raining 50% of the days I was able to hunt (work sucks).