Jumping ist totaly overpowered in all shooters. Everyone is hopping like bunnies (Well, me too ). You are much harder to hit and often even move faster.

But back to realism. I remember my friend buying a sniper game (don´t know the name now) where you could just sit and wait, often about 5-7 until anybody runs though your aim and get shoot and killed. Then you Changi Position a little, camping and waiting again...
Realistic? Yeah, a little bit. But in my oppinion boring as hell. (In real you often have to wait hours and more )
He liked the game much, so there are always different tastes.