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.