In the borders tab of various dialogs (e.g. Table > Table Properties...) there is a checkbox labeled 'Synchronize' that make sure that changes made to one of the entries gets made to all. It would be useful for this same functionality to be added to other tabs like Table > Table Properties... > Table > Spacing, Format > Image > Wrap > Spacing, Format > Image > Crop > Crop, Format > Page > Page > Margin, Format > Page > Header > Margins, etc.
Some times its useful to have it automatically checked, like how it is in the borders tab.
I don't like the idea to add another control that align two values more or less as the default. In some situations it makes sense, e.g. for images that shouldn't get distorted, but in other cases it's too much UI-noise, e.g. page size.
But I close this ticket as INVALID because it's not actionable. Feel free to file single tickets.
There isnt a need to open individual bugs for each instance of this functionality, we need to agree on which instances are acceptable and which arent. All examples mentioned in the description are about spacing and margins which are normally modified by the exact same value between the various fields, which is why these fields are unified into a single field in the sidebar.
I'm against having a sync checkbox for all dual-value properties. "All" might exclude one or some of your examples.