A cyber attack during holidays is not a harder technical problem than one in March, it is a harder decision-making problem. The systems fail in the same way, the forensics follow the same method, and the regulatory clocks run at the same speed. What changes is that the people named in the incident response plan are unreachable, the supplier that caused the incident is running on a skeleton crew, and whoever happens to be at the desk usually believes they have no authority to act.