I use the bag early in bow season and right up until I start hearing aggresive contact. Then I switch to real antlers. If you have a good bag and really know how to use it, you can get by just fine during all seasons. I just like to be able to bring some racket when I want to.
For most hunters, loud, aggressive rattling may be counter productive. You really need to know what your deer population is composed of in terms of both buck age and sex ratio. That and what you see is what should guide your rattling. If the oldest buck you have is 1.5, you don't need to get loud and agg. Too much will scare off anything you have except coyotes. In the midwest and Canada, I could not get too aggressive. Here I almost never use the real things anymore.