I have no idea what the distance was. It took three hours for my buddies (we're all younger backpackers) to hike to the ridgeline above them while traveling with excellent cover from the elk. I could not make the animals out with my 8x42s, but we found the first one with my buddy's 10x42s. We could not find the two spikes in the group until I got the spotter out. If you're just searching for cows or if you're not concerned about points on a bull, I could see justifying leaving it home. It was very helpful for me to keep track of where an individual animal moved to in the trees.
Keep in mind, I took the pictures with a phone and no adapter, just free-handing my camera over the eyepiece. I also had a large disadvantage due to looking in to the sun. The scope is the Vanguard Endeavor HD 15-45x65 that was in the classifieds on here about a month ago. Camera is a Galaxy S8 Active.
I'm far from an expert on elk.
The group of ~40 pictured was bugling at first light when we got in to the bottom of that valley. I was heading up the hill to glass the area we were hearing them when I scared up a group of bucks. Three shots were fired and an hour and a half later when I got to that ledge to glass from, the elk hadn't moved. By about 2pm when my friends got to about 125 yards from them, one bull had taken ~6 cows and gone in to the timber (I assume to get water) and left the second bull and his cows in that opening. The bull was just lounging in the sun all day until the wind shifted and the cows discovered my friends. I doubt they would have moved from that area until late afternoon/evening if they hadn't winded people.