Skip Logic in Custom Forms | Ability to skip other fields based on selection

I have noticed skip logic doesn't work the way I expect it to in custom forms. It's more like "skip TO logic".

With display logic, you can SHOW a field based on another selection. You can't NOT SHOW a field based on another selection.

Example:

I have a "Standard Size" field that lists several size formats like A4, 8.5x11 etc. One of the selections is "Other (Please Specify)". When this selection is picked, another field "Size (width x height)" shows up.

I need this to happen for EVERY asset where size is a requirement, but NOT if one of the standard sizes is picked. I wish I could do this with skip logic vs having to put display logic on ALL my assets.