I’ve always understood them as either/or, although I always though people wput their preferred one first. Sometimes people will use both when they’re questioning or just want to test one out to see if it feels more comfortable, or sometimes they truly just don’t care.

Though I remember someone once wanted each specific pronoun to be used depending on what you were saying (i.e. she went to the store where their friend was waiting), which I would try to respect but honestly that’s a whole other level of thinking and I can’t imagine most people being this particular.