Are “in writing” and “at speaking” commonly used?

Question

On other language SEs, I often have to talk about spoken language vs written language. Those phrases can be a little heavy, and I'm looking for shorter alternatives.

There's a very convenient and short way to say this in my language so I checked for a translation, and my searches (1) (2) returned "at speaking" and "in writing" but they don't seem to fit.

My typical use case is this:

[Word A] is almost never used [in writing], but is very common [at speaking]. On the other hand, [a synonym for word A] can be used both [at speaking] and [in writing].

I'm almost sure that's not the right way to say that, how you would say it?

Answer 1

"In writing" is common, but "at speaking" is not. Instead you can use "in speech"

"Gonna" is not much used in writing but is very common in speech. On the other hand "will" can be used in both writing and speech.

In general you use "in" as the preposition with a language or type of language. For example: "in formal language", "in French", "in slang", "in the Breton dialect", "in text messages".

You can use "at speaking" in expressions like "He is good at speaking". But you can also say "He is good at writing" or "good at tennis". This meaning is different from the above.

Answer 2

[Word A] is almost never used [in writing], but is very common [at speaking]. On the other hand, [a synonym for word A] can be used both [at speaking] and [in writing].

[Word A] is almost never used in written English, but is very common in spoken English.

On the other hand, [a synonym for word A] can be used both in spoken and written English.