What is the origin of the idiom "twenty-four seven" and when to use it?

The phrase "twenty-four seven" originated from the numerical representation of 24 hours a day and 7 days a week. It is derived from the system of dividing a day into 24 hours and a week into 7 days, which is widely used worldwide. It is commonly used in situations where round-the-clock service, support, or access is emphasized.