Despite the cries of the experts, all of photography partakes of an element of "spray and pray" in which the photographer takes many images and hopes that some small percentage of them work out to be excellent images. Photographers, even the ones that decry spray and pray as the domain of fools and n00bs, brag about how many images they throw away. Photography may be alone in this. Other fine arts do studies and so forth but there is a clear notion of progress, of ideas tried and either discarded or taken up. Photographers always take as many frames as time and patience permit, because they know that one of them will be the best. There may also be a progression of ideas, as in a painter's series of pencil studies, but there is always this element of shooting a lot and throwing the lesser ones away.
There are reasons for this, it is not simply that the photographer is stupid. The photographer has to work with reality, which is not so malleable as paint or words. The photographer begins with what reality provides.
Thus, every photographer accepts a degree of serendipity, of accident, in his work. There are moments which come along at which the photograph is simply better and all we can really do is hope to hit them with a button press.
As I have noted before, photography is unique in that the merest accident, a piece of equipment knocked over by a stray dog, can produce a powerful and moving piece of work. There are degrees of serendipity.
Regardless, the act of sifting through the results and picking out the good ones is an inherent part of photography. Even the greatest proponents of pre-visualization don't claim a 100% hit rate (although Adams may have claimed a number as high as 50%. If he did that is surely a record, and almost surely false). Henri Cartier-Bresson has been accused, half in jest I think, of having his "Decisive Moment" in fact at the contact sheet. The "Decisive Moment" is not when the shutter fires, but when the red pen circles the small image. To an extent, this is certainly no more than truth.
The result of all of this is that if you accept photography as art, you must accept that serendipity is permitted to play a role. I suggest that you may even have to accept that pure accidents might be art, but that is perhaps pushing it too far. Art is then not entirely about the artist's intent, about the "concept" if you will permit the term.
Because of these features of how the photographic process works, one cannot help but suspect that the concept perhaps antedated the photograph. One wonders, always, how much serendipity was in play here, and how much concept. How much, in other words, did the artist contribute, and how much was dumb luck?
In the narrative of photography as art we find such things as Gary Winogrand's 12000 rolls of film in various states of un-edited-ness, all edited up by a cadre of experts after his death. From this, 25 (or some similarly small number of) images were drawn as a sort of retrospective. Good god, how can we possibly know anything of Winogrand as a photographer from this? For all we know he simply hurled his camera at the ground repeatedly.
The current darling of "street", Vivian Maier is in much the same boat. Again, we have something more than 100,000 negatives from which has been drawn a couple of shows and a couple of books. A few hundred images. She is accused of having a unique vision, an astonishing eye, blah blah blah blah. How on earth can we know?
Pull 100,000 images out of flickr, or instagram, at random. You'll find some good ones. Wander around the city blindfolded pressing the shutter button at random 100,000 times, you will without question create some great images. Vivian Maier may well have been a truly great photographer, but whether she was or not is certainly unknowable without access to the complete files (something I venture we're unlikely to get, since she's been turned into a money-making venture).
The worst of this though is surely the artist who has some show and a book about something banal and stupid. America's strip-malls, say. Perhaps the artist sought to strip away the veneer of something or other, and reveal to America her own soul. We cannot help but suspect that in fact the artist sifted through 50,000 terrible images on their computer and noted that they seem to have a lot of pictures of strip-malls. A quick artist's statement later we're off to the gallery and the printer, aren't we? Well, with a little luck, a little pull, and a few connections we are.
Perhaps this is why photography feels itself always at the fringe of art, and why photographers always feel the need to defend photography as art. Its serendipitous nature allows us to craft the "concept" well after the work is made. And that feels like a cheat.