Absolutely, you have to know the nature of the trees in the hiking area, and you have to know the general nature of the bears in that area.
When you get up close to timberline, the trees are very short, and they are spaced far apart. When you get close to the swamp, the trees can be anything, and they are so dense you can't move through them.
I've had to use more than 50 feet on some hangs, but that was back in the pre-canister days.
Also, many bear cords are brightly colored. It would be better to have one that is darkly colored to make it harder for the bear to find. They work to locate the food by several means. First, they go by instinct and memory of where other backpackers have camped in the past. Then they sniff around to find the tree with the hang. Then they try to see the cord and the bag. If you have a dark cord and dark bag, they may get confused and try to climb the wrong tree. I've had that before, and I got the photo. I used black cord after that.