Data breach: 72 hours period extended on weekend?

Abstract

GDPR requires companies to notify data breaches to the supervisory authority „...without undue delay and, where feasible, not later than 72 hours...“1 Sofar, the notice period of 72 hours would include weekends companies were required to organise an urgency duty Saturdays and Sundays for the DPO and for relevant IT staff. But with reference to a EU-regulation dating from June 1971 the notice period shall be extended on weekend.