Is it important to have the leaves hang on the branches as long as possible. Like a shingle oak! Does that help at all?
Much like Big8 said, my experiences say it helps initially.
Someone asked about timing. If you're going to rub/scrape route, like Big8, I can see how it's matter when you "planted" them. My route, not so much at all. If planted in April, it sticks out like a turd in a punch bowl and is located where deer are feeding that time of year, they most often are used as lick branches. Even when you do lose all the leaves before season starts, it's already turned into the local coffee shop and the regulars are often are stopping by to keep tabs on everyone else. Once that happens, so long as it has a lick branch, what it looks like doesn't really matter.
Buckly nailed the positioning strategy I use. I should have explain that better. There are 2 reasons I use them: for scout cams and to give me a shot. For hunting, I'm placing them out far enough in the plot to get the "turd in a punchbowl effect," but close enough to the stand to give a reasonable shot. Pointing the branches towards the stand both helps position deer for the shot, and focuses their attentions away from me, while I'm in the stand. That generally allows me to get away with a lot more movement. I personally don't try aligning them with trails or anything more than placing them out from where my stand is. Sometimes the stand is there because of a trail. Other times it's there because I can slip out of that location easier. There's other times that it's just a pinch in the food source. I can't say I personally have noticed any difference in use or how fast bucks enter the plot, based on where the scrape tree is planted vrs trails. That may well be a combo of pressure/lack of pressure and/or buck age structure, though.
Someone else mentioned they don't have much luck with them. Big8 said he has most every deer check his, but speculated that "may" have something to do with not having a lot of mature bucks. In my case, I don't believe maturity has anything to do with it. Some locations, I get very good use from every buck. There are a handful of locations that they pretty much ignore it. Then there is everything in between those to extremes. I don't think it's a world changer every time in every location. It's just another little thing that one can do that may change the world when it matters most. That said, I've seen no differentiation in use based on age. With what I do, the oldest bucks in the woods are hammering them where the youngster are. When the old bucks aren't using them much, none of the other deer are either.
Now, what I am convinced does have an impact are deer numbers. In areas of lower deer numbers, I tend to have a bit of a higher % of the lower end results. In higher deer numbers, more of the "almost every deer checks them out" extreme. I believe that's merely the competition factor. High deer number areas, all deer have to work harder to establish their spot in the dominance ladder.