Rattling is usually good following extreme weather, when animal movement has been restricted. Coordinating your trip with a herd's sexual activity is the key to consistent success. It's then when bucks looking for a fight are anything but subtle. This is mostly evident a few days into the rut or toward the end, when does are still hot and many already have bred. It's during this time of diminishing availability of does that competition is greatest.
Nothing breaks down a buck's guard more than a narrow field of hot does.
Mature bucks tend to respond better to rattling toward rut's end. Young bucks respond from the time they separate from groups until about two weeks after the rut is complete. Many of them will be taken prematurely. To hit it just right takes either luck or time spent in the field observing deer behavior. I was hoping to bring the luck.