...First, the biggest red flag I saw in your original post was that you felt you needed to scout the venue. I understand why you wrote that. Heck, I've probably given that same advice on this forum...but that is usually to somebody who just got their camera and thinks their new DSLR with kit lens is going to cut it. They scout it, figure out they can't take a picture in those conditions, and we never hear from them again.
I won't say that scouting a venue is a complete waste of time, but the thing about photographing weddings is they are all hard. Either you have the skills and equipment to do it or you don't. As far as scouting, you won't know what the light setup is going to be until you get there. The DJ is probably going to bring lights, the venue might set them up, but rarely are the lights going to be the same from one day to the next. You have to walk into the room, figure out where the shots will work from and where they won't. You also need to figure out where all the 'core' shots are going to be...cake cutting, toasts, etc. And you have to know where you need to be to get those shots and make sure you get there before it's announced and a guest has taken your spot. Now, most of that is for the reception...
Ummm... What? I'm sorry Kerby, I normally agree with your thoughts, but in this case, I'm going to have strongly disagree. While weddings are NOT by any means my primary interest, I would never take on one without scouting the venues first. As the saying goes, 'time spent on recce is NEVER wasted!". Yes, weddings are all hard, some are harder than others, but I couldn't imagine showing up at the church on the day of and asking, "Anyone know where they're going to stand for the ceremony?" I've received some excellent advice and suggestions from the various Rectors and Deacons; they've seen hundreds of weddings, and can make suggestions such as, "One photographer went over there and did this... the couple told me he got some great shots." You're absolutely right that conditions on the day of will never be exactly the same as the day of the recce, but you can often get some good ideas. IMO, a venue recce is as essential a part of the photographic process as a pre-event consulation.