Although I studied Spanish for three years in high school and two semesters in college, it wasn’t until I had the opportunity to visit Mexico repeatedly that I become more fluent. Full immersion in a culture that speaks the language is the best way to learn and live the language.
So if you want to learn radian measure, then you must frequently visit the country of Radian. Fully immerse yourself in radian measure. Dipping your toe in the water and complaining (it’s too cold/too warm/too wet) is pretty much a non-commitment. Be strong and wrestle conceptually until you dream in radian measure.
If you want to learn radians, you need full immersion. Experts say that once you can think in Spanish (or any foreign language), you will have arrived. Once you no longer need to think in English and translate to/from Spanish before speaking, you will have become fluent in that language.
Likewise, thinking in radians (i.e., fractions of a half circle), will open up the flood gates to better understanding radian measure.