Which is all very well but... there are photographs that simply won't wait. Most social situations, for example, where human interactions are the story (weddings being an example): certainly there is a skill in prediction but this will only get you so far. Of course one wants to be aware, to be alert and alive to possibilities, to likelihoods even, but the unexpected still happens, happens all the time when it comes to the minutiae of facial expressions in fact, and quickly pressing the shutter button regardless of your camera / lens settings, even "spraying and praying,"* is, I'd argue, acceptable in such circumstances and can result in the best photographs of the day. If you've read any of my other posts you'll know that I believe that the aleatory plays to the camera's main strength: freezing the fleeting. In addition, sometimes the time spent faffing - even the quickest photographer has to spent a second or two changing settings - is the time in which the subjects face changes from natural to camera-aware and the moment is lost. In these circumstances it is worth firing away - sure, maybe a faster shutter speed might have helped but sometimes, sometimes, Life intervenes and you have to go with what you've got in order that spontaneity isn't lost.
"Wait a minute - can you remove your arm please? Also, do you mind if I set up this reflector behind the groom as I don't have quite enough dynamic range to work with? Right, I'm ready - can you run through that again?"*"Spraying and praying" is a derogatory term used to describe photographers who take a zillion photographs of a particular subject in the hope that one or two will "work" - it suggests a photographer who doesn't bring much to the table.
There are a million exceptions to the above of course - astrophotography, for example, likely runs on the principal of removing chance, removing the aleatory, from the equation. Similarly with fashion (models are paid not only for their beauty but also for their ability to look warm and happy after six hours on a cold windswept beach waiting for a break in the clouds), and feature films (actors - the clue is in the title). And yes, being prepared is of course vital ("The more I practice, the luckier I get," as Gary Player said someone once told him): don't go to photograph a football match with a pinhole camera and a wide-angle lens. But bear in mind that SOOC and "getting it right in camera" only go so far - chance and serendipity make great companions for photographers.