Assumptions pending, here are some observations I have made about learning Mandarin songs:
- In ten hours, split over a period of several days, I can sing intermediate-difficulty songs correctly by reading from Chinese characters.
- I can understand 70% of songs learnt to this level when listening to them.
- In thirty hours, split over several weeks, I can memorize songs and sing them without reference to lyrics.
- I can understand 100% of songs learnt to this level when listening to them.
- I can understand 10% of intermediate-difficultly songs I have never seen the lyrics for, regardless of how many times I listen to them.
Examples of intermediate-difficulty songs:
That is all.