In reply to David Millar.

If your gallery is always placing images side by side instead of automatically adjusting to the screen size, that sounds like a theme issue. A four-column gallery, for example, should probably adjust down to two columns on typical tablet display and one column on a typical mobile display in portrait mode. Manual control of those things could become a burden over time as technologies and screen sizes change.

With that said, I could see the argument for that level of control under some one-off situations where they are needed. But, typically, these are best handled globally on the theme level.