It's all a matter of personal preference. More often than not, a defensive style of gameplay is more rewarding than simply barreling through the map without releasing your finger from the trigger. Undoubtedly, there's a number of players that are quite good at doing the latter; however, they're 'good' and nothing more. When you're able to incorporate offensive or defensive tactics dynamically based on the situation at hand.. that's when you will be at your best.