big : if youre worried about your bow exploding if its held for 3 seconds , you will short draw every time. its like flinching if you shoot too big of a gun.
put your bow on the tiller tree and pull it with a rope and pulley. if you cant hold it there for 5 seconds , at the very least , i would say thats a pretty bad bow.
my board bow was at the full draw peg for a couple minutes at a time. i pulled it a couple inches past 28" just to know that if i stretch out or someone picks it up , there is a margin for some error.
i wouldnt hesitate to hold full draw while hunting even for 5 minutes. the only concern i have , is that it seems to cause a little more set. if i was really shooting , i would get to half draw , ready , then come to full draw as a shot presented itself.
also , your shooting left sounds just like me when i shot off my knuckle. now i shoot off my fingertip.
one other idea , is that with the bulbous handle , it may be twisting just enough in your hand that the arrow is actually moved slightly off the plane. try wrapping some athletic tape around it and build it up just a little. i bet this is whats happening.
-hov