Schmyd,
I have taken a sighter to check my wind call and then killed a whitetail immediately after. I have also not taken shots on game because I just wasn't confident. Last year I passed on an elk that I felt was within my effective range, it was just moving in some trees and didn't want to try a snake one in. I also went home empty handed that trip. This isn't just at long range, two seasons back I passed on a <50 yard shot on what would have been my biggest whitetail because I just didn't feel confident with the amount of brush between us.