I'm occasionally asked by prospective wedding clients whether I visit the venue in advance of the wedding day to have a look around and familiarise myself with the place.
This is one of those things that some photographers use as a part of a sales pitch - that somehow them visiting venues in advance makes them more professional. Personally I really don't see the point. It may be helpful for a photographer specialising in formal groups and portraits to have some ideas for possible locations for setup pictures, but for a photographer shooting in a candid, documentary style, it defeats the whole approach.
The whole point of documentary style photography is to capture what is happening on the day, wherever that may be happening. If a great picture happens in the car park then it's still a great picture, regardless of whether you visited a year previously and decided that under the tree in the garden was a good place for pictures. What happens if there's a lorry parked in front of your chosen tree? Or if the tree fell down six months ago?
You cannot predict the weather or the lighting, and you definitely cannot predict what is going to happen on the day.
A photojournalist needs the ability to quickly assess the current situation and adapt to it.
Obviously I make every effort to find out about the location, directions, parking etc. - the practical stuff to do with the logistics of the day. But I don't concern myself with finding out the light levels, where the bride will be sitting, or whether there is a photogenic tree in the garden. There's nothing I can do about any of that stuff, so I deal with it when I get there on the day.