I'm not sure about the "not efficient" part either. My password is 10+ characters, random alphanumeric with special characters. I sometimes mistype it. Whereas I'm yet to make a mistake tapping my finger on the finger print reader.
My current passphrase for work is 55 characters, so yeah, I could definitely see using this hack if I had to use sudo often.
(I'll probably shorten it soon, but it's a slightly mangled lyric from a popular song, so it's easy enough to remember.)