3 Cascaded SR(74595)

Okay I found the <Shifter.h>. I could change my code to utilize this header file because it allows access to bit by bit. However, I want to stay with the simple minded code I already have. My code has 3 SRs totalling 24 LEDs. We are using a bike rim to mount the LEDs so I’m working with 1 column. Do the SRs have to shift 1 byte at a time or can I shift a byte to a designated SR. With 2 we could use highBYTE/lowBYTE but how about 3 SRs? I have 3 sets of bytes, each SR has its own array of bytes for the entire duration of a revolution. In a loop, each delay represents a time slot. We are using 120 timeslots therefore at each timeslot I need to shift to all 3 SRs their respective hex code at the same time. The project is a POV Globe projecting a smiley face. (2 eyes/mouth.) Basically all LEDs one color and black out the eyes/mouth. I think this could be simple enuf for a newbie.

Here’s 8 daisychained.
When you need an update, send out 3 bytes at a time.
Shift registers won’t care if you send in the same data they already had.

if(time for an update?){
digitalWrite(ssPin, LOW);
SPI.transfer(byte0);
SPI.transfer(byte1);
SPI.transfer(byte2);
digitalWrite(ssPin, HIGH);
}