I spent some 20 odd years as a wedding photographer, after navigating a City & Guilds in general professional photography back in the 'wet process' days. As others have said, not a genre that allows screw ups. I stuck rigidly to the mantra of 'repeatability', carrying out pre-job checks and equipment packing exactly the same way, each time, every time. Exposure measurements and camera operation (Mamiya RB67) were also uniform, exposure to exposure, job to job. That way, anything going awry was easy to spot immediately. It was 'manual operation only' all the way.
With the ability to absorb any and all the stresses inevitable in that line of work, I guess I was well suited to it but as time went on (and as others have reported), client demands just went up and up and up, until (for me) it became absurd and I stopped with the advent of digital photography. There were still pleasant, reasonable customers at the end but the majority were quite different and failed to grasp that I could only get out what they were prepared to put in (ie I needed their full attention and co-operation to give them the fullest coverage).
I don't regret the experience, I just won't ever be repeating it again!
When it comes to choosing a photographer, my advice to family has always been - don't employ family / ask to see the last three complete weddings from your nominated photographer / ignore 'the studio book' containing the cherry picked 'best bits' / check every web review available (filtering those that are misplaced and/or unreasonable) / anything less than 100%, walk away.
I guess the advent of multi-function digital cameras has seduced some into believing it makes them 'photographers' and that all that's required is to auto-everything, dial the drive to max, point and shoot; whereas a bullet proof sense of calm, total mastery of the equipment and a clear agenda for the shoot (transparently shared with the protagonists) is key.