Usage of ABAP Program RSDDTREX_ALL_INDEX_REBUILD

Hi Experts

What is the usage of ABAP Program RSDDTREX_ALL_INDEX_REBUILD?? From other notes and SAP Library, I could find out that it will "Delete, Rebuild and then fill all Active BIA Indexes".

However according to my understanding, whenever data is loaded into the Cube, if that cube is on BWA, data will be automatically updated on BWA. Then what is the need of this ABAP Program??

Also can you tell me how frequently this program need to be executed? Or is it that it should be executed only on need basis?

Thanks in advance.

Regards,

Deepak