Am on BlackBerry therefore brief.

The Wiki article has references to the original thread from which the Wiki passage was compiled. Read that thread, things may be a tad less simple than "slow is bad".

And as with all things that require repetitive movements at high speed (musical instruments, chopping vegetables, martial arts), being able to perform the movement at slow speed is the key to performing it with precision at high speeds. Boring, but a proven path to success. The butter knife method may actually be a viable alternative to trying this with a razor.