Experience from this year isn't as wisdom inspiring but I bumped several deer this year from being a little sloppy, getting too close to gullies while sneaking around and skylining myself in areas I didn't respect or expect to have deer (but did) - this is high plains of KS btw. Just need to slow it down. I use 20x binos exclusively for spotting (with a tripod) and when I'd get to an area I'd have to cross that exposed me, I'd glass for 5-10 minutes, look for deer and if I didn't see any I'd continue through - well even 20x aren't good enough if you're in a hurry as deer have pretty good vision out to 700+ yards and can tell if you're not a cow or something else on 4 legs - I just didn't really pick apart the terrain to look for all of the deer in the drainage I was covering - saw a few does I thought I could sneak past but a few others at around 300-400 yards spotted me and that's when about 20 or more got up (incl a monster) and hit the road. Really regretted that one.
Ultimately had a very successful year this season but last year was more informative - hunted CO's second rifle and hiked into a great set, used a four wheeler to get to a secluded part of the mountain that most trucks/jeeps couldn't get through and then hiked another 3 or 4 miles into the wilderness area where we set camp. On the first night, we about got snowed in and had to completely change up our plan. My best friend had hunted the same unit earlier in a different area/different elevation during archery and found some great muley habitat while elk hunting and gave me the details. The deer in the area were really only about a mile from the parking lot but were bedding in dense pine woods (with like 20 yards or less visibility in general). I think the snow had them holding tight to the cedars and while I walked around 10 miles scouting the majority of the area, I stuck to what I knew at the time and just tried hunting high points with good visibility (had an elk tag too). The first evening, I bumped a few does on an open knob that ran back into the cedars. On my way out of the woods that first evening, I came out down a clear cut and saw a ton of tracks going in and out of the cedars and even walked within 20 yards of 5-6 does that were holding to the edge of the trees that I pushed back into the cedars. I didn't hunt into the thick stuff but came back over the next couple days and hunted the high points with lots of visibility hoping to see elk and deer and their travel habits. I always heard during second rifle deer would be in the dark timber but ignored or didn't think still hunting through the thick stuff would be my best strategy. I didn't see a damn thing moving during the 3 days I hunted. But on my last night, we walked back down the clear cut I referenced and cut through the cedars back to the truck - there were tracks and beds everywhere. I really missed an opportunity to find deer by not getting out of my comfort zone and just still hunting through the thick stuff. Maybe the lesson on that one is if one strategy isn't working and you know there's something else to try, just try it (especially if all the clues are right in front of you)