I highly agree with your approach out of a long experience of learning languages in unconventional ways. At the age of twenty I looked back on several years of English and French lessons without being able to communicate fluently and efficiently with any native speaker of those languages. Studying grammar never had worked out with me and traditional school books also had not been a great help.
Since then I reached fluency in 5 languages by being creative in constantly looking for new ways to grow into a new language. For sure the quickest ways are to live in a country with the target language or to share life or apartment with a native speaker. If this is not given I would advise to find your own personal way to surround yourself with the language and culture you want to grow into.
I personally made great experiences with re-reading books or simply picking my favourite author or theme in the new language. I know the style and what it’s about so I get the main message and if I did not understand a chapter well enough, I just read it again. My absolute favourite is listening to audio books. Here I find professional speakers presenting the literature I like and am connected to. It’s demanding focus and not as easy to digest as music but it’s highly efficient in learning contextual understanding. To start with I agree with the above suggested 40–60 percent understanding level.