My friend once said this to me about keeping an audience's attention in movies...
"If your friends grab you and kidnap you and take you into their car on your birthday, it's crazy. Where are they taking you? this is nuts! Five minutes go by and you're still laughing because they've tied you up and thrown you in the backseat and you can't see where you're going. After fifteen minutes or so of driving along, the novlety has worn off and you actually really want to know where you're going. After thirty minutes, you don't care, you'd just be angry and wanting to go home."
Note that I would hate to have my friends to this to me anyway - but it's something that I've seen done and to each his own... since it's really just a meaphor, it applies.
His point was that after a certain point in time - not too far in, your audience wants to know where they're going - or they are going to be upset.
Now - here's another twist though. What if they grabbed you and threw you into a car and you're all laughing and then about a minute into it you laugh, "Ha ha ha where we going?" And then your buddy learns over and said "We're going to the bowling alley."
....oh.
Well... that kind of took the fun out of it.
It's a delicate balance - what to withhold and what to reveal. I think learning dramatic rythm is learning tension and release. You stretch the mystery like a muscle just to the point that you can't take it anymore, and then you relax it so it isn't injured.
Now... the trick is.... as you let one mystery go - you must introduce a new one to keep the audience going. If you don't then you're just tied up in a car waiting to get to the bowling alley. So, one must weave mysteries... during the first mystery - you are setting the stage for the next mystery so that by the time the first is revealed - the audience will not have found pure consonance because they're already curious about the second mystery.
You can also make one powerful paradigm shift or "turn around" which answers one mystery and simultaneously introduces another. Both work.
What doesn't work is letting the mystery go.
I found that the first half of THE MATRIX was a lot more interesting than the second half and that while the first movie was interesting, the second two were dismal. The first half of the first matrix was so strange and curious. Who were these people - was it real? What is this place? What is going on?
Think about the second movie. Was there a single mystery in the entire film? Not in my mind. I felt like the entire movie was just labor. Step after step of tasks.
This goes beyond movies though. People can sustain careers based on this same principal. Artists can re-invent themselves to remain relevant. It can be done through their work, their image, or by being notorious.
Michael Jackson had a boyhood career, then a young adult career which was totally different and re-invented, then he became notorious later in life for being an unusual character.
Madonna would re-invent her entire image nearly every album and then began to create more controversy about herself with the photobook and other public image operations. And all of these kept her interesting to the public.
Some artists need to re-invent themselves, they feel irrelevant.
Actors can be re-invented - Keifer Sutherland with 24... before that he was "that guy who'd been in a few 80's movies." John Travolta with Pulp Fiction ("That famous 70's movie heart throb.")
No one can get away with making the same music or same movies without eventually become stale. No writer can keep their story alive without introducing new mysteries either.
Even financial people will talk about "falling in love with the story of a stock." They talk about stocks as having stories. Suddenly a stock will seem fascinating because of some news about the company - everyone is all a buzz and wants to talk about the stock and the company and they want to buy it... then it becomes stale and nothing new is happening - no new products, no new announcements, the story becomes stale, they sell, the stock plunges.
All things have this pattern and mastering the ability to create mystery can be used by anyone in any field.