Shooting from a rest gives you more insight into the mechanical accuracy of your gun and ammo - its potential under the best conditions. Prone is equally as good.
My original post wasn't aimed at the seasoned competitor that has thousands of dollars wrapped up in his custom built Bianchi or competition pistol. These individuals expect excellence for their dollars, know what they want, and will certainly test their pistols.
What I had hoped to do is get the average USPSA or steel shooter to discover if the pistol he bought from Billy Joe's Gun Emporium, or from Billy Joe's cousin, actually hits where he aims it! If his favorite blaster and load won't consistently hit a 6 inch paper plate at 25 or 30 yards how can this shooter possibly improve his skills when nothing he try's helps?
An acquaintance from North Carolina was about to quit competing because after two years of practice and competition, he wasn't improving. After many late night consultations, and much direction, he discovered his guns couldn't hit the broad side of a barn. (It wouldn't have taken so long if he would have listened in the first place) He fixed that problem and he quickly progressed to winning C class at the 2010 Single Stack Nationals! He's now a "B" shooter and having more fun than he ever imagined. His equipment almost drove him out of the sport!
Lets not lose any shooters for reasons that can be avoided.