It could be more like Layout like this place we will make swimming pool, or park or may be room design layout. More like a map. This could be done with scales and drafter. In our engineering we used to design top view, front view and side view. Even for simple structure, it would take half hour easily. Katha should be very fast.
Just imagine they are suppose to take 5 days for designing Dubai heritage auditorium with so many people, how can they design in just 2 hrs with only 1 person.
Anyway another creative liberty.