During the summer, I spent too much time covered in citronella oils that any scent control was pointless. Had to play the wind.
As the weather cooled, I was religious about using pine shavings in my bee smoker on all my clothes. I'd smoke it up before leaving & again at the trailhead. For my late season hunt, I'd make a fire at camp & burn oak & bay laurel to help with the scent. In all cases, I got busted just as easily when the wind swirled or changed as if I was wearing insect repellent. Most of those mishaps were within 100 yards. Granted, those were all after the rifle season so the deer were particularly jumpy. But, although it makes sense that it would work, I'm now skeptical that it makes much of a difference.
Regarding sage, we have many kinds of sage and even sage brush (different species entirely). I don't have a deer's nose. But I mostly smell sage brush when walking through it as I break or crush the leaves, stems, etc. By late summer or fall, our sages are done growing and only really smell much when being trampled. So as much as it could be a cover scent, it could also be a warning that something is coming.
But there's only one way to find out for sure...