'Usual' in the Bible

As usual, Paul went to the synagogue, and on three Sabbath days reasoned with them from the Scriptures,

Then Paul took the [four] men, and the next day he purified himself along with them [by submitting to the ritual]. He went into the temple to give notice of [the time] when the days of purification [ending each vow] would be fulfilled and the usual offering could be presented on behalf of each one.