In modern Chinese, words with meta-rhyme are common, such as "Yuan, Han, Kan, Lan, Gan, Slow, Mountain, Leisure, Drama, Fantasy, Life, etc." But in Mad Men, only the words "day, year, money, ship, code and time" are used as pledges.
Generally speaking, the rhyme requirements of the poem Madman are strict, and all the words can't be used as rhyme except a few specific words. This also reflects Du Fu's high degree of self-discipline and strict requirements for poetry creation.