I have seen the reference most recently when it comes to payment systems, but “24-7-365” is becoming widely used to connote something that is always open. It is short for “24 hours a day, seven days a week, 365 weeks a year.”
But there aren’t 365 weeks in a year. There are 52 weeks in a year. Thus, this expression is nonsensical.
A correct expression would be 24-7-52: 24 hours a day, 7 days a week, 52 weeks a year.
An easier, equally correct expression would be simply 24-365: 24 hours a day, 365 days a year.
A less accurate, but seemingly acceptable expression, would be simply 24-7, with an understanding that seven days per week means every week, and not just some weeks.
Also an option, for those more verbal than numerical: always-open.
That is all.
Disclaimer: The views expressed in this post are those of the author(s) and do not necessarily reflect the position of the Bank Policy Institute or its membership, and are not intended to be, and should not be construed as, legal advice of any kind.