....... "the only rule is that there's no rules". Clearly that's an exaggeration, but the point was to get them to think outside of the box and not get locked into bullsh*t like syllable counts, perfect rhymes, etc.
FWIW, all the truly exceptional writers I've ever known and worked with never read a single book or took a single course on songwriting, they just did what came naturally......
Bingo.... write from the heart and if you have something good to say, it will shine through. AS for following the rules.... they are guidelines to be appreciated but adhering to them as though they are the holy grail probably isn't a good idea.
Listen to the radio in any decade and you will hear people who are breaking every rule in the book and their songs seem to rise to the top regardless because they connect with the soul of the listeners.
They say you should have rhymes in certain places.... something I wrote last year was posted here and I really didn't think about it much....Then one individual pointed out there wasn't a single rhyme in the song.... I looked at what I had written, I read the lyrics again.... they were right... but nonetheless, it worked and resonated well.
Point being..... write. And don't be overly obsessed about following the (so called) rules. Write from your heart and soul and see what happens.