Back in the days of the Cultural Revolution, some Brit reporter type was put under house arrest in Beijing. He passed the time by concocting cryptic crosswords. (For the uninitiated, the kind with twisty clues that may be anagrams or run-on words or far-to-seek associations and puns that often as not make you work backwards ie once you have the word you look at the clue to see how the two can possibly fit.) They were eventually published as Crosswords from Beijing. After doing 30 or so of these he grew tired of the occupation and said, more or less, 'so I began learning Chinese instead'. I'm afraid my response to that was 'why on earth didn't you start doing that before you left England?' It was news to me that foreign correspondents would report from countries whose language they could neither speak nor read, and be considered reliable.
However. I am under house arrest, sort of, and it's taken me two weeks, but I'm now doing what I should have been from the start- or even before that- and reviewing my kanji. Once every ten years whether I need it or not, and oh boy do I need it.