You made me curious, since as I am guessing you might be thinking, 1:15k for IOF long, but what about classic? It appears OUSA requires 1:15k for F21 unless otherwise approved.Relevant OUSA rules
A.20.3 Technical Rules
A.20.3.1 MAP: Scale 1: 15,000 is required for M/F-21+ courses, except when another scale (e.g., 1:10,000) is approved by the Sanctioning Committee. For all other courses, 1:10,000 is standard, with Contours 5m or 2.5m, or other intervals if explicitly approved by Sanctioning Committee. ISOM standards apply.