Mahler: best known for symphony no. 5
Beethoven: best known for symphony no. 5 and no. 9 (ode to joy)
Shostakovich: best known for symphony no. 5
Dvorak: best known for symphony no. 9; Why is it for so many composers, either their 5th or 9th symphony is most well-known out of all symphonies they composed. Look at this: