That's our instruction as well.Get there fast! Its not how high but how fast you drive. The arms will match the speed of legs, so speed up the legs to speed up the arms
When we have a day to work on improving speed, two of the drills are:
1. Focus on really, really fast arm circle (as legs will have to catch up)
2. Focus on really, really fast leg drive (as arms will have to catch up)
Now I think we can all agree (perhaps) that a strong leg drive and a quick leg drive are correlated to some degree. Hard to go fast without going strong. But yes, there is a difference.