I'll start it off with mine, where there were a couple of "what if" moments that might've meant the difference between me being able to release an arrow, and not.
I had just snuck into 50 yards of a bull that responded to my locating bugle. I didn't know exactly where he was until I hit that roughy 50 yard mark and heard him raking a tree just beyond a few small pines directly in front of me...I could barely see him through those trees, but could tell he was facing me, and that he was big. If he stopped raking and went to my right, he'd go slightly downhill and cross through several lanes between 20 and 30 yards...goes to my left, and I'd have one lane as soon as he turned broadside, before he'd hit some thick brush beyond that one opening. If I move to my left to give me that one lane, the lanes to my right would disappear...if I stay put, the lane in the left is not an option, but the ones on the right still are, and means I don't have to move and potentially spook him...if I step to my right, the one lane on the left disappears...what to do? Being a rookie, my one big unknown was how much movement I could get away with while he was raking, since he was raking while facing me directly, and would rake for a couple seconds and look up...he was expecting another bull in the vicinity given my bugling sequence leading to that point.
I stayed put, hoping he would go to my right. He went left, and 5 yards quartering away uphill and moving away from me...I bugled to try to turn him back down to me...what if I popped to the left while he took those few steps away from me? The bugle turned him back down toward me and raking another tree, still at roughly 50 yards. I waited him out again, and figured it was a better approach not to spook him, and give myself a chance to hunt him another day(this was only day 2 of the hunt). Now he turned to my right and headed down for the various lanes I had there...heart pounding, I draw my bow and wait for him to get to where I need him. He hits the last tree I would've needed him to pass, and he turns directly away from me, behind the tree, and continues away at a slow pace, but never looking back...I let out a sequence of cow calls/bugles, which got one final response from him, but not enough to get him back in...what if he had taken two more steps?
What makes all of the "what if" moments tougher is that, not realizing it in the moment, is that the forecast changed and weather would force me down off that mountain to ensure I didn't get my rental truck stuck 9 miles in on a sketchy road...what if I had been more aggressive in that first encounter?
This is replayed in my head every day.
Another: Last year we went antelope hunting in Wyoming. Bad weather kept us out of the field for most of two days and the rain kept the goats off of the water. The last morning, I got in my pop up that I had set the night before. The nicest goat on that end of the ranch came in about 9:30. When I wallowed my bow off its holder, (due to shoulder pain I couldn't lift it straight up), he must have seen or heard me. I had the mesh off the windows of my Matrix 360 blind and he was close. What if my shoulder wasn't bad ? What if I had elected to shoot through the mesh ? We will never know, but y'all know what I'd like to think don't you ? :-)