I love this site. I went through every lesson like 6 months ago because, although I could type prose very quickly, I had not mastered the programmer typing that it takes to quickly experiment on the unix shell or hit opening braces and parens with consistency.

Although typing certainly isn't a big development bottleneck, being able to type fast lowers your overall cognitive load and lets you stay in the problem domain you're working on.

It's not like loud noises are a programming bottleneck either -- but it's certainly nice to eliminate a nuisance.