Suppose you have a web form, with some fields being optional and some being required.
One of these fields is a combobox or radio button group, for which a valid default option is pre-selected and it is not possible to "un-set" this field.
In other words, this field is always valid for submission, but potentially not correct, and I can't have users "glossing over" that field as many will with all of the "optional" fields.
Should this field be marked "required"?
Note: I would prefer to keep the default pre-selected option, because this value is the correct value for more than half of the use cases by volume.