I'm going to go out on a limb here and say this is where and why I feel so fortunate to have cross trained in Kung Fu San Soo with my Kempo. KFSS is practiced slowly, yet when demonstrated shows amazing speed and unbelievable power (
I've still got bruises from practices as much as five years ago at maybe 1/3 speed/power).
Jimmy Woo (the founder of Kung Fu San Soo) said to go fast, practice slowly. Here's what I think he meant (it works out as a syllogism, for the literati out there

).
Practice the basics
slowly (with good form--many have mentioned alignment);
then over time, this proper,
relaxed form breeds speed (muscles are not tightened to restrict movement--some have mentioned newer people going fast and wrongly thinking they're generating power); and
finally,
good form plus speed generates power, at least in the body-fighting arts, which put some weight into the strikes.
Too much of the Kempo I was taught was about arm power. In another lifetime, my boxing manager would equate this arm power to a jab--good in its place, but not anything like a hook. When he talked about the left hook, his eyes lit up behind those coke bottle lenses (he'd been a ranked middle weight back in the day). He made it his trademark because the hook may only travel a few inches, but with the trained body behind it, and to the right target, it became a knockout punch.
Now is there a place for the quick strike, the jab if you will? I agree with those who have said, Yes, as a spear hand or open tiger's mouth (web hand) to the throat; no need for body power there, arm power is more than enough. Same with eye rakes, fingers to eyes or throat, etc. But I wouldn't use these or count on these to work as a flurry (doesn't mean others couldn't do so, but I wouldn't bet my life on
me being able to do this). If I get in the first strike, one of these would be a very fine start. But if we're already in it, one or two and at the most three good Kung Fu San Soo type shots should do the trick. If not, I may be in for a long ride.