TVC, aren't there lots of cases where the suspect is considered armed and dangerous due to the crime? I know car theft, armed robbery, escapee, and bank robbery are, and that is why they are drawn on during engagement. Lots of people make stupid moves when being confronted by cops. Personally, one of the scariest positions that officers can be in, and it happens probably more than any other, is pulling a car over at night and the officer is by himself. Walking up to that vehicle has to be unbelievably scary. I don't envy that officer at all.
I'm going out on a limb here and say that there is no amount of training that can help any officer make a split-second decision not to fire when a suspect has a gun and is waving it or pointing it at police. I have no training and I would not let him get off the first shot.