Even though I have a large list of images in my wallpapers folder that my desktop slideshow comes from, I still see a lot of the same images over and over again. Is there a way to make it sequential or more random(I assume not, since it is probably already random)?

The code does support sequential sorting internally - but unfortunately it offers no ability to configure this and is hard coded to randomise.
If you're able to compile a Plasma wallpaper, it is a one line change to switch to sequential sorting.

In regards to making it more random - unfortunately this is not possible either. Unfortunately the code does not have any limitations placed on it with regards to showing previously shown images, so it can repeat the same images fairly easily.

There was a recent commit (for 4.11) regarding more randomness in wallpapers.

Hi,

We're trying to get the xkcd "Time" comic to play sequentially as a desktop background. I gather from this thread that it's not possible without a lot of extra work. Boo.

Feature request, then.

I ended up doing it by setting up a folder with one image and a 'slideshow', then used a script to rotate in the correct image.

This is just a wish list item. I see that this has been discussed several times and is not a show stopper by any means. I may be wrong but it seems that many years ago the slideshow wallpaper feature offered the ability to select sequential or random presentation. I would greatly like to see the sequential option as an offering again. I know that there are much bigger fish to fry and this is not a major issue, but it would be nice to be able to have this option. I would even suggest sequential as the default with random as an option. Keep up the good work.