Elk hunting and a bull is coming in. You draw your bow just as he is walking behind a tree or bush at 25 yards so you can take an easy shot just as he steps out. Well he doesn' t want to cooperate and decides to have a look around before continuing on his path. You have no shot and can' t let down the bow because the only thing visible on the elk is his head and neck and he would surely see you if you twiched. You have two options. #1 keep holding at full draw hoping that he will take just one step or #2 let down and say by by to that big 6X6.
Good example.
With my longbow, I hunker down while he' s behind the bush and wait to draw until he steps out and exposes his chest, hit anchor and the arrow is on it' s way in less than two seconds. And all the time I' m hoping he doesn' t see the movement of the draw. It' s NOT an easy shot, but that' s bowhunting.
You, on the other hand, drew while he was behind the bush and couldn' t possibly see the draw. You' re sitting there holding a drawn bow until the shot is presented. It' s a very intelligent approach that definitely stacks more of the cards in your favor, but... Isn' t the number one argument against crossbows that an animal has the chance to catch the bowhunter' s movement when he draws and the crossbow is predrawn so there is no drawing motion? What you do in your example is not so very different from using a crossbow.
I hope you can see the fundamental difference that I' m trying to show.