Tea and timeframe

A relatively unsatisfying 20 min. sketch here. Charcoal pencil on 5 1/2" x 8 1/2" sketch paper. This was the first time I was looking at the timer wondering what else could I add to fulfill the 20 min. requirement? It probably took me 15 min. Next time I attempt a subject like this will be in color, with a more challenging (and interesting) composition, so that I have plenty to do in the timeframe.