RE: Do you use a rangefinder and which type?
Yeah, you're probably right...lost animals due to less than accurate shots are great woodsmanship skills. By the sounds of it, you haven't missed a single animal to this point due to your exceptional estimation skills and gritty personal hunting involvement.
Just my two cents.
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."
--Albert Einstein