In my observation, it is very common. That is, many plans define service w/ 1000-hour rule. The plan may have separate definitions for vesting service and benefit service, but (practically) those definitions are identical. Upon reaching a plan entry date (very often defined with a one-year eligibility period and dual entry dates), the employee will always have earned a YOS and might be very close to earning a second YOS.
Or perhaps I've misread the question.