If I remember it right - Keith Hancock's song has a chorus wot went -

When I were a lad, Eeeeeee times they were bad, but not as bad as when my dad were a lad. When my dad were a lad, Eeeee times they were bad, but not as bad as when my dad's dad were a lad.

scansion? even with the tune and the songwriter singing it was so odd it had to be humorous even ignoring the text. The repetition of such simple words might be boring, they are not exactly erudite BUT there is a message powerful enough to make the humour even funnier, because it is truer - on more than one level. And the audience had to hear the chorus several times to prise-out the meaning. The puzzle referred to above. By then we could sing it - almost.
You can't write a rule for that - except the affect on the audience. And there you have it - know your audience's preferrences - how? go out and try - run the guantlet and don't listen to ONE person, take it all in.

Overuse of rhyme - so what - but Keith was at the peak of his songwiting then.