Keep in mind the laying out of a PCB, a matrix is compact but stretched out it becomes a can of worms.
Using SRs, the ICs can be kept close to The LEDs. If ring has 72 LEDs,( 9 SRs ), then its clock can be divided by 4
and used as the bar clock. Every thing stays in sync. Different patterns can be loaded, single circulating bit,
marque, inverted marque, or random pattern. I believe that you have seen the short videos of each.
Yeah, thankfully, PCB design is where my skills lay; it's just the digital logic part that confuses me.