Scenario
Silas is waiting for the 1 bus at Beacon Street because he has a gig in Harvard Square in an hour. His mind is preoccupied with thoughts about his Scoring for Strings project. He must turn in a main theme by tomorrow. As he ponders, he whistles a few notes. He pulls out his phone to check when the bus is coming, and then opens Musical Sketches. He puts the notes he was whistling on the staff, listening to their pitches through his headphones. As he places, he thinks of more notes. By the time he arrives in Harvard Square, he has a full theme sketched out on his phone, which he saves before his gig.
At home that night, he opens Musical Sketches again and browses to his theme. The theme he composed on the bus opens and he can see the notes on the screen. He listens to it on his phone as he transcribes it in Finale on his computer, where he spends the rest of the night fleshing it out and editing it, then turns it in the next morning.