Out in a canoe on a lake in the Adirondacks, we paddled along on a glorious summer day. I had my DSLR set up for shooting HDR, trying to capture cloud detail along with shadows in the deep woods along the shore. Small aperture, moderate shutter speed, ISO 100, exposure bracketing set to 2 stops over and under, all focus points active. Then an osprey appeared. It quickly flew to within 20 feet or so of the canoe and splashed into the water, where it briefly struggled with a fish. After staring in wonder and amazement for a moment, I replaced my mid-range lens with a telephoto, then fumbled through changing the camera settings - higher ISO, slightly over-exposed to compensate for bright sky, smaller aperture, turn off the bracketing, only center focus point active etc. Meanwhile the osprey lifted out of the water with its catch, winged right over our canoe where it hovered for a moment (I'm sure with its tongue sticking out as I cursed and fumbled) then headed for shore. My only shot was an underexposed, blurry image of the osprey's retreating backside. It joins the two shots I have of the blurry retreating backsides of moose, a shot of a stump with the retreating backside of a squirrel that had been sitting there, the lily pad with no frog... My attempts at wildlife photography have often been dismal, partly (mostly?) because that's not really my area of expertise, but also at least in part because I'm not always able to quickly adjust my camera for the unexpected both related to wildlife and other unanticipated happenings.
This was a factor in my choice of a new camera late last year. My Canon Rebel XTi has all the basics and a few bells and whistles as well, but it was unable to do more than one thing at a time - it had no way to save a configuration for quick recall. One difference between entry level cameras and those further up the sophistication ladder is indeed, this very capability. My new Canon 60D has one such custom setting. I can set up the camera in a desired fashion, save the settings, and then recall them later by turning the main program dial to "C". Since the vast majority of my missed opportunities seem to be related to action shots and wildlife, I've configured the "C" setting to what I would generally want for that sort of photography and now, with a quick lens change and a turn of the dial, I can switch from anything else I happen to be doing, to nab that osprey, moose or squirrel. Further up the camera sophistication line (in Canon-land anyway), the 7D and 5DmII each have 3 different configurations. (Nikon likely has similar capabilities, though I'm not familiar with them.)
Another useful customization found on a number of Canon cameras (and again, likely others as well) is the customizable menu option. On a modern DSLR there are an extraordinary number of menu items and it's easy to forget where something is and waste valuable time trying to find it. The "MyMenu" feature allows you to fill one menu screen with your most commonly used options.
Luck in photography, like so many things, stems in part from uncontrollable events, but it's tempered by being prepared to take advantage of unexpected moments. By the way, the panorama photo at the bottom of this page is from the same day in same general location that we saw the osprey!