"All the time", yeah. Relatively to that, I have to write individual greek characters very rarely, as they are not part of my usual script. Almost never, compared to a greek person.
The same applies to the scripts used by e.g. Chinese, Arabian, and Korean speakers.
So naturally I am not a "fluent" writer of ξ and ζ, and since I virtually always write those characters in isolation instead of as part of words, it's a different mode of practice even when I do use them.
It's the same on the keyboard, by the way. My keyboard does not have ξ or ζ keys, it's all special.
