It's like saying "half ten" instead of "ten thirty". There's a missing word, it's "half past ten", it's "friday next week".
For that matter, the missing word could be this, as in “Friday (this) week” versus “Friday (that (as in the next one after the one contrasted with via the word this) week”. I have no way to disambiguate this, so I ask something like “Friday after tomorrow” or “Friday the 13th” or something. It’s hard being me at times, I’ll admit.