Is the usage of particles preferable in writing?

Question

For example the particle "ja":

Wie du ja weißt, habe ich meinen neunzehnten Geburtstag die letzte Woche gefeiert.

Answer 1

Depends. When writing to a friend, and you write like you would talk, then it's ok. I'd still be careful to not overdo it as it can distract from your message.

I'd avoid it in non-personal writing, like in research papers, news, work products, and so on. It may be ok for a professor or teacher writing a book for students, but again, don't overdo it, if you do it at all.