Found a tutorial on how repeating patterns / wallpapers work. Decided to try it out with all of the wrestling illustrations I had for ASWG: Dark Match. It's pretty useful! The general idea is that you fill the space, swap the 50% vertical and horizontals of the images, fill in the space, swap the 50% vertical and horizontals again, and repeat until you're satisfied.
Since you're swapping the 50% each time, you're ensuring all the bleed will match up. I'm going to be doing a breakfast one in the future.
This seems like a good, basic skill to have.