PJ,
I'm not sure what you're reading, but you asked about "big Timber". I think your question might be more about glassing, than dark timber.
In parts of the west (Northern Idaho and Montana west of the Divide, coastal Oregon and Washington) the timber is unbroken. It goes on for miles. Yes there are pockets and burns, but mostly its very thick timber. This country is sometimes hard to hunt with a rifle because glassing is very difficult.
However, during bow season, glassing to locate bulls is less of an issue. Often you use your ears more often than your eyes. Heck, in thick timber the majority of the time you only SEE the bull just before you shoot the Bull!
On the other hand, when I hear "Dark timber", I'm thinking north or east facing slopes. Those patches of timber are more wet and thus thicker. Elk use these areas to bed and breed as stated above. If you want to know about Dark timber that's a whole other beast.
If your asking who hunts big timber, sure I hunt some big timber. To me it just feels like elk hunting . Give me huge tracts of lodgepole stands, with rubs on fifty trees from 20 years of rutting bulls, and I get pumped.
I also like to hunt burns.... that's kind of our thing. 4-10 year old burns are money for us. You can glass early and late and the new growth draws bulls from miles around. I use google earth and try to find east west ridges with north facing timber adjacent to burns. The flatter and longer the ridge the better. My hunting partner will probably shoot me for writing this.