What is the origin of the idiom "all hours" and when to use it?

The idiom "till all hours" has its origin in the concept of timekeeping and the practice of measuring time in hours. It suggests a late or extended period during the night or early morning when most people are asleep. The phrase "till all hours" implies staying awake and active long past the usual bedtime or working hours. It is used to emphasize the length of time or dedication someone exhibits while engaged in an activity, whether it is working, partying, studying, or simply staying awake for an extended period.