The area where I hunt is great whitetail/mulie crossover habitat, so I use a mule deer feeding doe Montana decoy when I do in fact use one. I have had great results as far as bringing and holding bucks within archery range but haven't killed anything yet. But what I mean by holding is having young bucks come in and try desperately to get the does attention for several minutes and she doesn't even give him the time of day. Kinda feel bad for the little guys, I've had the same problem myself in the past. So in that sense, plenty of time to a)distract the buck to draw your bow and b) offer a shot as he circles around the decoy.
But, I feel that they are time sensitive, meaning, they need to be used right around/in the rut. The Montana decoys are made of fabric so of course they soak up foreign odors. Won't take long for a buck that isn't driven to stupidity by testosterone to know the jig is up.
Last year, I was archery hunting during the rut and saw a 160ish muley 700+ yards out. It was a calm day and started wailing on the doe in estrous can. Sure enough, I called him to just to the edge of archery range (60 yards). He wouldn't come into the little clearing in front of me because he couldn't see a deer there so why would he? I had opted to leave the decoy at home for safety sake because some guys were rifle hunting the same property and they didn't know exactly where I was. Hindsight being 20/20, I was in no danger if I would have set up the decoy and I'm 99% confident that buck would have offered me a shot if I had the decoy out. He made an entire circle around me ranging from 60-30 yards grunting like a pig with his nose to the ground looking for that hot doe. This year, I will give him what he wants, a visual aid, and have the decoy out.