The people I shoot with have a little chant, "The shot is rarely taken from the prone". And, therefore, we learned to sling up and shoot comfortably in all sorts of positions - standing, sitting, kneeling, prone, supported and unsupported, etc. In the class I took in August, the last half day was an practical exam. On the first problem, I tried to shoot from a bipod and it was a mistake. The position was on a big pile of broken concrete, crummy position, multiple targets, limited time. After each shot the bipod hopped around and I spent a bunch of time repositioning the weapon so not all targets were neutralized. I should have shot off my backpack using the sling to stabilize the weapon. My shots would have been more accurate and faster. Live and learn. The tie-breaker was fired standing, 375 yards, steel silhouette, precision rifle. According to the instructors, both professionals, these things happen in real life and, by the way, it was hugely entertaining for both of them.