In 2012, my family and I planned a trip to Wyoming to hunt pronghorn. My goal was to get it done with an open sight revolver.(didn't happen) I prepared by shooting my SBH 44 out to 100 yards. My targets of choice were milk jugs, and I got proficient and confident at 100 yards.
Then I modified the cardboard deer they sold at the box stores to simulate an antelope. I set up my antelope at 100 yards and went to work with my 44. My shots struck danger low on the simulated goat. On the same day, same gun, and the same ammo; a center punch on a milk jug was a shot nearly in the legs of my cardboard critter. It tooks two clicks up on the rear sight to hit the animal shape properly.
My theory is that the highly visible jugs allowed me to sharply focus the front sight. I suspect that when sighting on the my spot in the vitals of an antelope, I lowered the front sight ever so slightly to see better over them.
Lesson learned. Now I know, my practice needs to be as realistic as possible.