People do full sheet engraves all the time, the issue with not loading must be with your file(s). Likely far more resolution than actually needed.
You should test at different resolutions (and lpi as mentioned above) to find the most efficient settings.
Lot of good information in here, but a couple of simple things got missed…when you are engraving anything, whether using the Photo Engrave settings or the vector engraves with Convert to Dots… (do not use Vary Power) …arrange your design into as few rows as possible. The machine is going to go back and forth like an old dot matrix printer, and much of the actual delay comes with how far the pattern to be engraved reaches vertically. So two rows with 6 patches in the bottom row and six patches in the second row is going to engrave in less than half the time of four rows of three…the way that you have it set up there.
Now I’m going to explain why I think the full sheet wouldn’t load for you.
When you are engraving anything…the head needs a certain amount of space on the sides to slow down. There is a gray bar that sets a limit on the left and right side of the bed when you have the design selected…if any part of that design falls onto the gray bars, the design won’t engrave or cut.
The size of the gray bars changes based on the speed being used to Print the file, so you can get a little more space to work with by slowing down the engrave speed, but you also need to reduce the power if you do, so that you don’t burn too deeply. It’s easier for beginners to just arrange the design so that it all falls inside of the gray bars at normal processing speed. It’s possible with that staggered arrangement that the total area is too wide for the engrave limits.
You can put as many patches into the rows as will fit, provided that the total area for everything does not exceed 18" wide and 10.5" tall at a speed of 1000. (Just fill up a rectangle set to that size on your artboard in Illustrator, then delete it.) That should enable the file to load as one batch.
Keep in mind that if you totally fill up the bed, the time for engraving is going to measure in hours, not minutes, depending on how high of an LPI you are using. For leather, you want to use really low power (1-2%) to just tattoo the skin, not burn through it, and an LPI of 270 or less.
That might not be why the file wouldn’t load though…those look like grunge fonts and those are typically pretty trashy from a construction standpoint…they can have too many junk nodes and overlaps. For those, the earlier suggestions to rasterize the images are very good ones. Just one suggestion…rasterize one patch, excluding the cut line, and then group that with the cut line before copying it in the Illustrator file and creating your batch layout. When you open it in the GFUI, you will need to set the engrave settings for each individual raster file once, but when you save the file all the settings will be saved. If you need to delete a few to fit it on the board for higher speed processing, or copy and paste one, you can do that if you treat them separately. You can’t do that if you just do one large raster file of all of the patches.
Batch processing is an advanced function that gets a lot easier after you have run a few, and you’re right…this isn’t covered in the training.
One last thing…please make sure that the “leatherette” that you are attempting to process is not a “plastic leather” or “pleather”. Natural leather only, or you run the risk of ruining your machine in very short order. 
Thanks for the excellent help in this thread, everyone. @Jules provided a great solution for this issue here:
Could you please let us know if this helped to get you printing more of your design on one sheet?
It’s been a little while since I’ve seen any replies on this thread so I’m going to close it. If you still need help with this please either start a new thread or email support@glowforge.com.