Not necessarily. The rule is one continuous year of qualifying employment within the three years before filing; if a continuous year exists inside that window, or the leave preserved the employment relationship, the requirement can still be met.
Look for the continuous year inside the three-year window first
Hypothetical example: The requirement is not that the manager has worked continuously for three years; it is that one continuous year of qualifying employment with the related foreign entity falls within the three years immediately before the petition. A Portugal Cove-St. Philip's operations manager who worked from month one to month thirteen, took leave in months fourteen to eighteen, and returned for months nineteen to thirty-six has two candidate periods, either of which may satisfy the rule on its own. Where no unbroken twelve months exist, the petition must show that the employment relationship continued during the leave: a leave agreement, continued benefits, a guaranteed return and payroll resumption are the evidence. The employment during the year must also have been in a managerial, executive or specialized-knowledge capacity, and time spent physically in the United States on business does not count toward the year even though it does not break it.
Hypothetical example: a company that produces custom orthotic devices wants to transfer its Canadian production director to lead its related U.S. operation. Prepare a month-by-month employment chart that identifies payroll employer, leave periods, job capacity, and work location. Then compare the U.S. organization chart with the proposed duties: deciding production standards and directing supervisors is different from personally fitting devices all day. Payroll records settle the qualifying-year question, while the two charts settle whether the future role is truly managerial.