Slides containing more than a few images take a lot of work. Not only do the images need to be high resolution, but they also need to be placed in a way that's aesthetically pleasing. This isn't too hard if I know the total number of images and their dimensions / aspect ratios ahead of time, but it quickly becomes tedious when I inevitably decide to add or subtract some later. With each change I end up needing to move most of the images around.
I wish there were a tool to help generate slides based on a config file. In other words, this tool would take the canvas dimensions and a list of image URLs as inputs, and then it would output a slide with the images distributed both vertically and horizontally without it looking too much like a grid.