Well, actually, this applies to all sorts of photography but more so any type of photography that has less controlled situations. With weddings in particular, one of the challenges is that things never go exactly as planned. Even when they do, specific moments can happen in split seconds and unexpected moments pop up all the time. Capturing those moments and being prepared is one of the keys to being a successful pro.
The above shot was just one example. I was walking the couple towards a new spot that I wanted to take some shots at, and I turned around and noticed this beautifully backlit image of the groom helping the bride with her dress.Since I hadn’t set up the actual shot I was going to take, I had luckily set some of the dials to what I wanted since I knew I wanted to shoot some backlit shots with the sun slightly coming through. I was able to get this shot because I did have my settings locked in and when I turned around to see where they were behind me and saw this, I was able to pull the camera up and get this with minimal adjustments (pretty much just adjust the zoom on the 16-35).
So the key is to always be prepared, and I know I can be a bit anal about this. Whenever I pack up my gear, I set my camera to ISO 400 and the f-stop to the most wide open setting. That way, just in case something crazy happens on my way home, I can possibly snap a decent shot if I have to pull the camera out in an instant. In most instances, you have a little more time that a millisecond, but you never know when that great image might pop up!