we usually type faster than writing,even though we are accustomed to writing very much, as the typing uses all the ten fingers, while writing we uses only one hand, so we can easily reach around 30–40 wpm by typing, where as it is difficult to reach 15–20 WPM while writing. as you know , touch typing uses muscle memory , and we can input one character in a single stroke, but writing needs combined effort of eyes and and entire hand, so we can reach great speeds by typing. some professional typists can reach around 50–80 words per minute, at smooth pace . even we can improve typing speeds drastically by practice,but writing requires all the hand co-ordination . so it is difficult to achieve higher speeds by writing, even after after getting good practice and experience..