29 C.F.R. § 541.701 : Labor — REGULATIONS RELATING TO LABOR — WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR — REGULATIONS — DEFINING AND DELIMITING THE EXEMPTIONS FOR EXECUTIVE, ADMINISTRATIVE, PROFESSIONAL, COMPUTER AND OUTSIDE SALES EMPLOYEES — DEFINITIONS AND MISCELLANEOUS PROVISIONS — Customarily and regularly

The phrase "customarily and regularly" means a frequency that must be greater than occasional but which, of course, may be less than constant. Tasks or work performed "customarily and regularly" includes work normally and recurrently performed every workweek; it does not include isolated or one-time tasks.

29 C.F.R. §541.701