I Learned French in 12 Months
I don't believe there is a shortcut for "hacking" languages.  I'm a diplomat, and currently learning my fourth language to the C1+ level.When we learn languages, it's a full time job. It was 9 months to learn Mandarin to a  B1, 6 months to a C1+ in Spanish, and I'm currently at a B1 in Estonian after 5 months.There are several things I think are crucial after years of full time study (note: this assumes you're going for professional fluency, not just touring around the country where interactions are largely scripted and predictable):* There is no substitute for production - you must speak the language with a native speaker (not an app) and talk about topics that are relevant to the kind of scenarios you anticipate. We spend the first several months discussing current events in target language - at first scripted, then later free form. This builds vocabulary and helps fluency. This is quickly expanded to discussing current events in depth and participating in mock debates.* Give mini presentations - target 3-5 minutes of talking about a relevant topic with little prep time. The difference between intermediate and advanced is the ability to move from discussing only facts to making a coherent argument. Native speakers will often not be able to follow your train of thought without learning to connect cause and effect using structures appropriate for your language.* Interview native speakers - prepare 2-3 questions about a particular topic and check your comprehension by translating their answers to English. This obviously helps build your comprehension, but also helps to learn to "automate" comprehension while you are thinking about something else. If you can take notes in English while a native speaker is talking at normal speed (and achieving 90%+ accuracy), it will make it easier for you to participate in normal speed conversations.* Read target language news - this is critical for expanding vocabulary and learning colocations - knowing what verbs are used in particular contexts (e.g., do they say "I talked with X" or "I talked to X". Do they say country X shot, launched, or threw a rocket?)Bottom line - language learning is not just about the number of hours you put in. The quality and type of practice you do matters a lot. You aren't going to be fluent via Duolingo alone.  You need to put in the time using structured practice with native speakers to really learn anything.