At the Lucas party, after Elizabeth plays a couple of songs,

she was eagerly succeeded at the instrument by her sister Mary, who having, in consequence of being the only plain one in the family, worked hard for knowledge and accomplishments, was always impatient for display.

It sounds like Mary barely let Elizabeth finish, and in fact, there were some requests for Elizabeth to play another song. Mary is so eager to display her accomplishments, that she isn't considerate of her older sister.

Then,

Mary, at the end of a long concerto, was glad to purchase praise and gratitude by Scotch and Irish airs, at the request of her younger sisters