Assume the Shift Register (SR) starts with all 0’s in the 32 slots. If you use something like C01, C02, C08, C02 for the 4 Theme inputs, you will generate a pattern of length 16 before it repeats. How do I know 16? You take the Least Common Multiple of the 4 counter values and then multiply that by 2, so the LCM of 1,2,8 is 8 * 2 = 16. If your numbers were C01, C02, C03, C05, the pattern length would be the LCM of 1,2,3,5 = 30 * 2 = 60. As you can see, using prime numbers and large odd numbers can dramatically increase the length of a pattern before it repeats.
Going back to 1,2,8,2. If you pick a high Shift Register number (I think 36), the pattern will be something like: 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0. These values will get stuff into the SR one at a time for each 16th note pulse:
1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,...
1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,...
1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,...
0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,...
1,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,...
1,1,0,1,1,1,0,0,0,0,0,0,0,0,0,0,...
1,1,1,0,1,1,1,0,0,0,0,0,0,0,0,0,...
0,1,1,1,0,1,1,1,0,0,0,0,0,0,0,0,...
1,0,1,1,1,0,1,1,1,0,0,0,0,0,0,0,...
1,1,0,1,1,1,0,1,1,1,0,0,0,0,0,0,...
0,1,1,0,1,1,1,0,1,1,1,0,0,0,0,0,...
and so on. So by picking any single slot of the SR to use as an input, you’ll eventually see the repeating pattern come out. Picking 2 or more SR slots to use and you’ll generate what initially looks like a random string of numbers, but will eventually resolve itself into a pattern.
other tricks - use a custom scale and load in the same value more than once to weight that note value more heavily. Works great if you pick notes that trigger a drum machine’s instruments (for example) and you can generate complex but repeating drum patterns.
The Rhythm menu only has 2 inputs, so you can only generate 4 different values. GT1 and S/H only support 3 different values, so the middle one of each is twice as likely to occur (50% 16th note). Since there’s 256 choices of density, what I do is pick a density, then set the first two values to C01, C02 and listen for the variety I want while changing the Density value and then use counters/hard values, or the SR to vary those first 2 in various ways.