Not even a year ago I used only my ring, middle, and index fingers to type. Not even my thumb for spacebar. This is what I call "The Velociraptor"
One day, I said to myself, "I type like ****."
So I took a large portion of my day and the following days to correct my typing by only pressing keys with the finger that was supposed to be used in that column.
I started at a grueling 40 WPM and it was highly discouraging when I was typing at a snail's pace and I wanted desperately to go back to the velociraptor but I remained vigilant.
Now I can type at around 80 WPM which is pretty much what I was typing at before... One might say that my efforts were in vain as I didn't improve much at all, but my typing experience is much more comfortable.
Also: I don't actually press the "C" key with my middle finger 100% of the time. When I have too type a word like "cockatrice" I would use the middle finger for the first two Cs and then in order to press the E immediately after the C, I would have to press the C with my index and then the E with my middle. Hope that makes sense.