In a fight, to hesitate is to lose. It's worse than not hesitating and making the wrong choice. Kiritsugu didn't hesitate at any point, even if he was every now and then caught by surprise by the new developments. But you could clearly see in this episode that many of the grunts didn't possess such mentality. You can say they should be pros after a fashion, with international cooperation training and whatnot, but did it really look like that? Besides, training is just training. It can never replace real experience. There are things you can't train, at least not fully, like the mentality of a killer. Still, like you said, their pre-operation preparation could probably have been better. It didn't really look like the troops were appropriate instructed about what to do if Plan A fails.