After I practiced and increased speed from 250 to 380 char/s, the effect was that I started writing in IM larger messages and explaining things more thoroughly.

After I practiced and increased speed from 250 to 380 char/s, the effect was that I started writing in IM larger messages and explaining things more thoroughly. This became much easier than earlier. So I'd agree, that you may write down things quickly or write a lot more in a minute. For coding this means you easily write comments, for messages or articles means you can write a lot more in one moment, which means you write a lot more elaborately.