Big timber Blacktails take scouting and more scouting and most scouting. Scout until you find tracks that look promising. Drive roads looking for crossings. Once you find the crossings, verify whether it's one, two or several animals and whether it looks like they've traveled that trail numerous times. Look for a set of tracks that are deeper than the rest. Mature Cascade Blacktail bucks can out weigh their does by 50 lbs.
Years ago on the Beckler Peak road while Grouse hunting, I noticed a deer trail that came out of a wall of brush and crossed the road and vanished into a rock wall loaded with brush and ferns. I checked it numerous times throughout that fall on my trips through and it always had sign on it. One of the late Novemberish Grouse hunts when I was parked just down the road from the deer crossing, I had just loaded the dogs, shut the hatch and turned around. There standing in the road beside that trail was a brute of a Blacktail buck with a smaller buck beside him.
They're out there and those bucks that live up high in the cascades can get huge bodies.
Couple years ago outside of Forks, hunting the late season. Didn't know the area so the kid and I drove hundreds of miles on numerous roads up high until we found one lone set of deer tracks on the end of a logging road. Numerous trees on the end of that road were trashed. One lone buck lived somewhere close but we couldn't find him. We saw a hundred elk or more that weekend and one set of deer tracks.
Many years ago on the Foss river road during late bow season, driving roads looking for tracks, I crossed a set of tracks. Went up the road, parked, walked back down the hill to check the tracks. They were big, deep and looked fresh so I followed the tracks down the hill about a quarter mile and ended up in a wall of vine maple and walked right up to a Blacktail buck laying in his bed that looked like he belonged in the Chiwawa drainage. He knew I was there long before I knew he was there so he won.
If you want to see large numbers of deer, hunt timber land with 5 to 7 year old clearings. If you want the chance at a Blacktail of a lifetime, hunt high country or private.
It wouldn't be unreasonable to think you could hunt public land all season long and see one deer but that one deer may be a stud.
Good luck Out there!