Scenario # 2.5 or #3, you have the bad guy dead to rights and are going to shoot him, instead you blather on about how or why you're shooting him and something happens to let him get away. Monologing is the downfall of villain and hero alike, any kid who's read a comic book can tell you that!
Scenario # 4, you are approaching the bad guy's home to question or arrest him and spot him on the street walking toward you. He shows no sign of recognizing you as a cop and will walk right past you if you do nothing. Instead of letting him do so and grabbing him, you immediately call out his name, identify yourself as a cop, tell him not to move, then are forced to chase him down as he runs away with a half block head start.
Scenario #5, the bad guy merely starts to point a gun at the cop, who immediately puts several rounds through his heart and one through the forehead insuring his immediate death, which results in the loss of vital info like the location of the buried kidnap victim with 30 minutes of air left. He is never so quick to fire before or after and when he does shoot another bad guy, he often misses vital areas and the guy is only wounded or he has several minutes to question him before death.