Commons:Overwriting existing files/invalid

Rillke's quote: I see no benefit at all in scrubbing. It neither does it make the SVG easier readable (by humans) nor do we need to reduce size or similar since our SVG renderer converts them to a PNG thumb and caches the PNG. I'd say: "Never change a running system", especially if it isn't required. Making invalid SVG valid or removing references to raster images that don't exist is ok but this isn't the case here.

A detailed essay can be found at User:JoKalliauer/Optimization, which explains

1. when files can be overwritten
2. which elements/attributes (even if they are invalid) should be kept and why
3. how to optimize/repair files