[HD] Yooara (HELLOVENUS) VS Lee Jinwoo (KPOPSTAR 2) - Atlantis Princess @TVN 

It's not continuous hit of a note, it's hitting the note well enough to register as a hit on the program. The program have certain parameter and thresholds that determine whether it's a hit or not. It doesn't mean they are singing perfectly through the whole song. And also, you can see that they didn't hit some of the notes as well, as evidence by the red in the blue bars