2) Writing in different languages exposes what you do not know
When speaking on the fly, you are likely to converse about daily life topics or revolve around topics you are familiar with.
However, in writing, you might be tasked to express thoughts and ideas on an unfamiliar topic.
This then becomes a true test of your communication and writing skills as you are now exposed to what you do not know, you are forced to search for new vocabulary to describe the unfamiliar topic.
This then enhances your language skills to be able to express yourself confidently on a wider range of topics.
For example, when staying in Thailand, I had minimal issues when communicating with Thai locals on topics surrounding day to day activities. I was easily able to tell the Taxi driver where to go and was able to order meals in Thai.
After I returned to school in NUS, I decided to take advanced classes to learn Thai in Singapore. That was when I really became captain of the struggle bus 😫I struggled to write Thai essays on complex topics such as the education system, foreign workers and even the gospel in Thai!
Writing in different languages then exposed what I did not know how to say in Thai and helped build new vocabulary to enhance my Thai language skills.