That applies to many people, but not to all.
> Jonathan现象，再一次证明了语言输出的能力不依赖输出的练习。“说”的能力是并不需要大量“说” 的练习的，所以不要再误认为学外语必须要“多说”，关键是先要会听和会思考。
I disagree. The ability to speak is not the same as the ability to speak well. That is, you may be able to speak (1) very slowly and (2) with heavy accent. But that's not nearly the ideal you want to achieve. Being fluent in a foreign language (as well as speaking with correct pronunciation) is just as important as being able to speak. And to achieve the goal of fluency needs a lot of practice. (Having good pronunciation needs practice too but to a less extent.)
A very good idea if you don't have a chance to speak to a good (possibly native) speaker. The biggest advantage is that you have lots of time to do so. The disadvantage, however, is not to be discounted: (1) not knowing or knowing well whether you would be understood; (2) not knowing or knowing well if your pronunciation is correct.
Good point. I often tell my friends to chat with me in messengers. Messenger-chat is even closer to actual speaking than writing on your own because of its interactive nature. Again, there's clear disadvantage, i.e. the second (2) one above for speaking to yourself, pronunciation.