In T 664/00 the appellant (patent proprietor) had requested an adjournment of oral proceedings due to a public holiday in the USA. The board rejected the request as national holidays in individual contracting states are not recognised by the EPO for practical reasons (see J 5/98). To allow for national holidays in non-contracting states throughout the world would be even less practical. See also T 2125/11.
Source: http://www.epo.org/law-practice/legal-texts/html/caselaw/2019/e/clr_iii_c_6_1_4_e.htm
Date retrieved: 17 May 2021