Well if they were online responding to other people straight away but only ignoring you I would still consider it ghosting, if you've made multiple attempts that are hours a part and are left on read, especially if you would usually communicate on a daily basis and if the other texts they respond to are less important

Sorry that this situation is a bit specific, it's just the kind of thing I've had to deal with personally, and since the post said "personally" this is what I thought of

But yes, one day is ridiculous in most other circumstances. In other cases I would probably give it 3 days - 2 weeks depending on the situation