How is that faster than just making the change to a regular Time Machine backup?
I think Jake kind of gave you this answer in post #2
In the past, when internet connections were much slower and where many Mac users had modest WiFi download speeds, Apple devised a system that would compress data when one did a TM backup. As mentioned before, this used sparsebundles which created internal links so that any additions to data from one BU to the next could be handled in the shortest time possible.
As WiFi and internet speeds increased over the years, it became less of a burden to prepare TM backups without compression and it opened up different formats which were faster & more efficient.
For example, in the past, a TM EHD was formatted Mac OS Extended (Journaled).
Nowadays, a much more efficient and faster option is available by formatting the EHD as APFS (Case-sensitive). This came about because APFS is designed for SSDs and all recent Macs have an SSD as their main drive and it is formatted APFS. Thus copying data from the Mac's SSD to a TM EHD also formatted APFS is faster & more robust.
HTH
Ian