Don't know if there's a way to tell for sure, but the first coat often takes longer, and uses more product, because of the small irregularities in the surface.

Second and third coats go on much more smoothly and quickly.

Also, water-based latex or acrylic paint dries quickly.

And if they used a sprayer to apply the paint, those very fine, very thin Mist-like droplets dry even faster.

Oil-based paints take much longer to dry.

Are there empty paint cans around?