Gun guys have adopted without much thought the idea of shooting from unbalanced and unsupported firing positions as the way to go. Its a bad idea all around. This is 3-gun stuff only. But American Mercenary said it best....
I call B.S.He's exactly right. Click here to read his blog.
I'm on my third deployment and never had to shoot laying on my side, or know anyone who has. I've been through the AMU's SDM and CQB train the trainer courses, and I've trained in CQB with the AWG. That is my resume. None of those units train any sort of "laying on your side like a Hollywood action hero" form of shooting.