Can I leave any label fields on elements blank?
Label fields for elements (meaning, any field which fills in text to be shown on the element to a visitor) cannot be left blank or empty. The default field value will be applied if there is nothing in the field. A recommend workaround to this is to use a space instead.
For example, the button text label of a Donate Button cannot be left blank because there really should be a description of what clicking the button does, but technically it is possible to save the Donate Button with a blank space for the button text.