Using a battery-operated device continuously for four hours would run down a battery faster than using it for an hour on, then an hour off, for four cycles.
The reason is that batteries have a tendency to recover a little bit if not used for a time.
A battery’s current comes from electrons that are a byproduct of a chemical reaction between two substances, and how those substances are physically arranged affects how the reaction proceeds.
They actually move from one side to another.
The rest period time allows the ingredients to equalize and lets the liquids get where they are supposed to be.
There is some recovery with continuous use, but if a battery is used until it is completely dead, you get more service with intermittent use than with continuous use.
The difference between intermittent and continuous use is greater with a device that makes a heavy drain on a battery, a toy with a motor that runs wheels, for example, than with a clock with very light hands that runs continuously.
The physical arrangement helps explain why rechargeable batteries made with nickel and cadmium may exhibit what has been called a memory effect.
For example, if a battery designed for an hour of use is used for ten minutes and then recharged, and if this process is repeated several times, the next time the battery is needed for a full hour, the power drops off fairly quickly, as if the battery had a memory of what was expected of it.