Well, we know that when Paul spoke/preached all night long, it was from Saturday afternoon through Saturday night, and into Sunday morning. Because it says he preached into the night on the first day, and the only "night" on the first day was Saturday night (since the first day starts at sundown on Saturday through sundown on Sunday).
So, if we say Paul preached here, then we can say he preached on a Saturday afternoon/evening/night.

Grace is not common.