Great thread.
As mentioned by others. My number one item is my wind checker. Nothing happens moving fwd without wind knowledge. Then it’s game on.
For me as I age it’s not so much about what to put in my pack as it about what to omit from my pack now days. I find myself packing stuff I’ve rarely or ever used.
That might be a thread of its own. “What to omit from your gear/pack”
I fully agree with this... My pack averages 5 pounds lighter then my dad's and I carry a liter more of water... He's 73... A couple years ago I went through his pack and took out a bunch of stuff I knew he wouldn't need... He could tell instantly it was lighter and couldn't figure out why... I finally told him him I went through his pack and asked me what I took out... I said if he could name it I'd give it back... He got one head lamp back... After the hunt was over I gave him back everything I took out... I think most of it's in his pack again...
I have to do this to my own pack every year before the season. I get the "I need this itis" and stuff mysteriously materializes inside my pack 
Last year after bear, muzzy deer, muzzy elk, half way through modern deer my dad was wondering why his pack was so damn heavy... I watched him go through it and take out 3 extra headlamps, one with a big battery pack and spikes from hiking in the snow in June... Among some other crap...

Like what! I go through my pack before each hunt... lol!