Any given message is delivered by each participant at most once.

He'd once delivered a talk there, a paper on naval strategy.

A competitor may choose any speech that was once delivered in public.

Food is delivered once a week (or less regularly) by boat.

The paper felt heavier than the ones the grocery boy delivered once a week.

The two had first met in the 80's, when they once delivered opposing lectures.

Meat, fish and dry goods are delivered once or twice a week.

Heating oil is delivered once a year, she pays in advance.

Food and supplies are delivered once every two weeks.

What fresh food we needed was delivered once a week, along with the mail, which consisted of drugs and other medical supplies.