An important part of photographing a convention is the coverage of each presenter's area, some of these can be very large. It's important to have access to the venue before and after convention hours. This type of photos is best done before each day's convention time because the areas are clean and organized, especially at a well attended event. Sometimes however, with large venues, the lights are not all turned on until just before people are allowed in. This is because it's very expensive to light these massive spaces, so if we can't get the lights turned on early, we have to get these images after the closing of the convention and maybe "clean up a little" in post, but never on the last day because the "tear down" starts even before the space is empty of convention goers.
Location: Mandalay Bay Resort, Las Vegas, Nevada.