Is a single expiation incumbent for multiple oaths, or is an expiation incumbent for each oath?

A Muslim should not swear excessively. As for someone who swears frequently without intending an oath, such as saying "No, by Allah" or "Yes, by Allah," or swears about something that turns out to be contrary to what he said, this is a "laghw" (frivolous) oath for which there is no expiation. However, if he swears to do something or not to do it and then breaks his oath, then an expiation is incumbent upon him for every oath he broke.