29 CFR 776.25 - Regular and recurring activities as basis of coverage.
Regular and recurring may mean a very small amount and is not to be determined by volume or percentages. Coverage depends on the character rather than the volume of the employee's activities. For example, if an employee in the course of his duties regularly engages in covered work even though the covered work constitutes only a small part of his duties, he would be covered in any week when he performs such covered work. 14
14 Walling v. Jacksonville Paper Co., ante; Mabee v. White Plains Publishing Co., 327 U.S. 178.