It seems quite common among language learners that living in a country where the language you learn is spoken is a very effective way to improve the language skill (especially speaking).
However, even living in such country, I found that there are only a few minutes in a day to get the speaking opportunity. Unless you work for a company or attend school, there is practically no chance to speak the language. Making local friends is also unrealistic as people only want to be friends who speak fluently, but unless you have enough opportunities to practice the language, you can never gain the fluency. (Also the possibility of making friends depends significantly on race, ethnicity, gender, age, etc...)
So I feel living in a country where the language is spoken don't get my speaking improved that much. I even think it is better to live in a cheap country to save money, and then attend language school in the target country. Example: Living in Ukraine for 3 months and then attending language school for 1 months in Rome to learn Italian, instead of living in Italy for 6 months.
This also jibes with my experience. As a perpetual traveler, it is common for me to travel to a country and stay over 1 months, but in all countries and all languages, my skills did see practically no improvement. Only after I attended a language school in China did my Chinese start to improve greatly, and it is even going to surpass my English (L2), which I use in any country as a traveler for long enough, but never attended any school.
I'm not going to say it has no effect. At least vocabularies should be improved as you see the language in restaurants menu, ads on the wall, etc... or everything you see in your life. But other skills, especially listening and speaking, would be very little, in my opinion.
So is the theory correct or myth? Is it often suggested solely because it is 100% better than living in your home country, as nothing whatsoever gets you anything better than living in the country? In other words, does it focus on the certainty, not on degree? Or is there any such evidence, research, data, that supports the theory?