I learned French and Spanish natively because of my family, but I speak other languages like German or Mandarin, although I only know the most common Chinese symbols I can understand people talking and communicate myself effectively.
The most important thing is not forgetting what you learn, specially when the neural connections are weak. For this I used Anki and my own tools.
You do not need to push yourself so much. In fact I do not recommend pushing yourself into a foreign environment without basic understanding, specially If you are an adult and need to function in that enviroment.
I traveled to Germany only after studying it for years 30 min a day. It was much better experience than in China in witch it was similar to your "pushing yourself" method where very few people speak English.
In China the rate at which I could learn was not better than if I had started learning that in Europe. It overwhelmed my capabilities.
Also, China is a different culture, and you have to learn it the hard way with painful misunderstandings.
I will say that I believe that it's not harder because of any innate fact but because people give up and go back to native.
My speech pathologist/therapist friends hate me.
We quickly learn how vulnerable we are without a local language or Lingua Franca.
In my experience working class immigrants who have immigrated to places that have no large established language community in their new home are the best demonstration of this. They often start with nothing but end up with great skills whereas others will just stay and interact with their native language community and be barely conversational in the majority language.
If you intend to move, then whether you practice Chinese for 4 years in a classroom vs. with Duolingo, any differences are going to melt away very quickly and what will emerge as the forefront factor of success will be one's innate ability to push yourself in a foreign environment; i.e., don't be safe and only interact with people who speak your native language.