Is that a requirement for the higher grade on a particular level?
https://youtu.be/_ha7eUK5glM?si=ka33uQ6VAfPbGmwx
The higher grades often require cake boxes, fast play or both. Some expert players lock pieces into place instantly using "DAS", where you hold the hard drop button as the piece spawns! It's very difficult, but with practice you can play incredibly fast.