When telling the time, are the following expressions legal or natural to native speakers:
e.g.: 1. It's thirty past six (without adding "minutes"). 2. It's half an hour past six (adding "an hour").
Also, are there any difference or restrictions between using after and past (Are they ALWAYS interchangeable)? And is it common to use preposition to in "It's twenty-three to seven"(weird for me because 6:37 is definitely more straightforward, so why bother say it the other way round)?