Leonor learned the value of long nights.
She, King Stephano, and Desmond got into transforming Piedmont into something worthy of tourists and a festival, she understood how easy it was to stay up late when you were busy with something.
A few times in her Academy years, she stayed up late to study. There was no forcing herself awake as they prepared the festival.
They would be so busy that she didn't realize how late it was until they stepped back from their tasks and saw the world had been overtaken by darkness.
Leonor was more useful to the organizers than she originally realized. Since all authority figures were men, they thought a woman's touch was necessary for decorations. Considering she was the duchess, they figured she was more than qualified.
Leonor thought of flowers when she thought of spring, so that was the theme they went with.