No it will not be a mistake. There's no way for SM to plot the photoshoot timetable round indiviudal attendees needs as it just wouldnt happen.
Yes, but you can plot the schedule far better than it currently is surely?
I mean, prioritising cosplay photos and putting them on at a peak time from 1.15 to 2.45, and thus pushing back 10 photoshoots till after 3pm...
in what bizarre world is this fan-friendly scheduling :)
You could easily have swapped those shoots around. Push the cosplay till later in the day - it's a GUEST-oriented event after all, not a cosplay focussed event.