How to divde an LED Strip into groups to display effects?

Using Arduino LEDs and Multiplexing
5

Grumpy_Mike:
Don’t do this

for (int i = 0; i < NUM_LEDS; i++)

For just using LEDs 0 to 4 ( the first five ) use

for (int i = 0; i < 5; i++)

Then do

for (int i = 20; i < 24; i++)

And so on to build up the colours you want to show on the LEDs.

@Grumpy_Mike big shoutout to you for this idea, it was a good starting point.

But the problem is that the effect is supposed to appear on special pixelgroups with gaps between each other.
So like I wrote in my first post, for example pixel 1,2,3,4,30,31,32 should show the same effect as a group. If they would have been in one row (from pixel 1 to 10 for example) this would have worked but I need them to be paired together with an effect that cycles threw all of the pixels of one group.
Any ideas?