Three act structure falls into a category I call “useful bullshit.” Typically arguments over three act structure become a tedious fight about whether it’s always the best or whether it even exists. It’s a mark of an educated mind to be able to entertain an idea without necessarily holding it to be true. Therefore, I like to think of the three act structure as something that’s generally useful, even if it’s bullshit.
As a practical example: horoscopes. They’re certainly not scientifically rigorous. But they do represent a popular means of understanding the universe.
I know a lot of beginning writers who are really into horoscopes and bad at differentiating characters. I recommend that they assign star signs to each fictional character. It doesn’t even matter if the traits they assign are even “true” to the commonly held traits of Scorpio, Taurus, etc. It’s just a tool that makes sure characters seem a little different (as added bonus, we might even get a fictional birthday for the fictional character we’re trying to fob off on the world).
There are many ways to conceptual the complicated process of learning writing. I find it’s better to ask not if something is true, but to imagine ways where applying the bullshit can be generally useful.