WP Smush Pro Multisite Settings.

I'm setting up WP Smush to work on a new multisite. On the settings page, it seems that the image dimensions to be optimized are dependent on which theme is activated on the primary domain.

If I change the theme, the image dimensions change and are not selected by default. I don't perceive this as a "problem" to be fixed, just wanting some clarity on what to expect. Do these settings need to be changed for each subsite on the subsite dashboard? Or are the settings on the network dashboard reflected across the network, meaning there will always be some images that cannot be optimized by this plugin?

For example, on the network dashboard, I can only select image dimensions that are applicable to the theme I have currently activated on the primary domain. When we activate new subsites, do I need to keep in mind that each subsite will need to have settings selected specifically for that particular theme? Or is the network dashboard the only place to make these settings?

The image dimensions I can select from the network dashboard are specific to the theme activated on the primary domain. If I change the theme on the primary domain, the image dimensions on the network dashboard change with it, and I have to go back in and select them. My concern is that I'll end up with many subsites (most of which will NOT be running the same theme) that have lots of images that are not getting compressed.

It's not a big deal, but I have clients that routinely upload thousands of images. If they cannot be compressed automatically, we will run out of storage on our server very quickly. One image from a digital camera can easily take up more space than several dozen images that have been properly optimized. Just wanting to be clear on what to expect so we can control the amount of space clients are using on the multisite. Ideally, I just want to make sure we're not missing images and taking up unnecessary space.