Yes sir, I get nervous when I first see a deer coming into range.
I'm actually better off if the deer just pops up in ML range so instinct can take over & as you said--I do the tunnel vision thang where all I focus on is behind the shoulder.
When I'm in the woods, all my senses are on point (until no critters are movin) birds,squirrels-pesty,possum,coons even mice are the entertainment.
Non-hunters don't get it!!
Anyway, after sitting in a stand for ?????? then appears the only big game animal we have in So. Illinois--Mr. or Mrs. deer (yes I shoot mature does).
Your damn right I get excited & have been for 27 years now. You just got to learn how to control it your best.
You gotta love the game or you shouldn't be playin!!

Mark