Wedding and event work, at its core, is documentary photography. While there may be brief windows of time where people are posed and lighting is controlled, the true art of this category of photography is the skill involved in being able to capture a beautiful image which simultaneously gives context.
A job well done here is a body of work that can transport you to re-experiencing the emotions of the day if you were there— and if you were not there, being able to be emotionally transported to that day as others experienced it.
The beauty, and the challenge, of this type of work is being quick on your feet and technically knownledgeable enough to absolutely nail the moment in a visually pleasing way.