Entubado (from the Spanish entubar, “to put into a tube”) is a traditional bunching method. Each filler leaf is rolled into its own tube, and then the tubes are gathered together and wrapped in a binder leaf. The aim is even airflow, giving a draw that is neither too loose nor blocked.
It takes time, and many factories use faster folding methods. Companies that still train rollers in entubado treat it as a skilled technique, not as a way to add flavor. A poorly made tube bunch smokes worse than a carefully made accordion bunch.
Entubado is a construction method. The tobacco still has to be properly prepared. See how cigars are made for where bunching fits in the overall process.