Writing advice is never etched in stone. You can break any “rule” provided that you can pull it off. But generally speaking, you have more lee way to break away from the time-tested templates when you are shooting for artistic originality and while considerably less slack when you are trying to create a commercially successful story for a very wide audience. This is why high-budget Hollywood movies tend to adhere to story templates to a fault. When a hundred million dollar investment is at stake, you have to use every trick at your disposal to appeal to as wide an audience as possible.
Don’t mix genres. Keep the pacing brisk. Stick to the three act structure. Employ relatable characters. Stay focused on the main conflict. Keep it believable. Avoid one dementional characters. Stay within the story universe. Et etera. Et cetera. YouTube is full of film analysis and script writing advice that teach you to adhere to one principle or another. You can break one rule or two, but the more rules you break, you exponentially increase the risk of losing an ever larger portion of your potential audience.
Of course, there are exceptions. The most glaring of them being Bollywood action musicals. These movies usually run between two-and-a-half to three hours. The plot is frequently composed of two or more separate stories. They contain elaborate musical dance sequences in the middle of a spy epic or a crime drama. They veer between Buster Keaton style slapstick and serious, sometimes tragic, story lines. The characters are mostly walking cliches in spite of having lengthy back stories. The action and chase sequences are deliberately outlandish. (They make James Bond’s submarine car look plausible.) The conflicts and tension points are all over the place. If anything, they seem to be bending over backwards to take the viewer out of the story. They are exactly the opposite of how movies are supposed to be written.
How do they get away with it? It seems to have to do with how the movie maker deals with the perceived diminishing attention span of the audience. Ever since the rise of the “movie brat” directors – Spielberg, Lucas, Coppola, Scorsese, et al – Hollywood movies have become faster paced, more action packed, and tightly structured. This was based on the idea that audiences had shorter attention spans and therefore could not be trusted to stay attuned unless you fed them an unrelenting barrage of stimuli. Contrast Rogue One (2016), for example, with a Golden Age classic like Love is a Many-Splendored Thing (1955). The latter, a winner of three Oscars with a run time of 102 minutes, feels at least twice as long as Rogue One which runs 133 minutes. But Love is a Many-Splendored Thing, featuring a war correspondent making frequent trips to the battle field and a cross-racial romance (albeit played by two Caucasian actors), was a tightly packed movie for its time. Hollywood has been making tighter, faster, more intense movies ever since in an effort to keep the audience’s attention.
Indian movies take the opposite approach. Given that casual movie goers would not be very emotionally invested in a film in the first place, why expect them to remember whether they were watching a comedy or a tragedy five minutes ago? This is how a serious cop who did a Tom Cruise style action sequence shows up ten minutes later wearing a ridiculous fake-beard disguise in a comic turn of events, then breaks into song and dance another ten minutes later, then goes back into serious drama mode, and still manages not to break the entertainment value of the movie. Factors like consistent cinematography and color pallet do play a part. But the basic assumption is that the audience who was entertained by the dance sequence will be just as entertained by the chase sequence a few minutes later and that the tone of the story does not have to be consistent throughout the entire run time of the movie because the audience will cry anyway when the musical comedy ends with a tragic death.
Novice writers who insist on breaking away from established story structure tend to believe that they are moving closer to Neil Gaiman or David Foster Wallace by doing so. They should be forced to sit through several Bollywood productions if that is the case. Because even if their writing becomes a success, it is much more likely to end up a mishmash of story elements than a literary masterpiece.
That may come off as an insult to Indian movies. On the contrary, Indian cinema gives us an alternate form of film entertainment. One that authors of fiction of any genre should very much be aware of. Popular entertainment CAN break all the rules. But you do not break them by accident. You have to be meticulously aware of exactly what kind of an effort you are getting yourself into.