[tshaddox]

I was referring to leap seconds, which are applied at the end of the calendar in UTC, and are the only cases where UTC is not a continuous and predictable time scale. A scheduling system like cron still needs to have some mechanism to handle events that are scheduled in UTC, because particular UTC seconds can be skipped over. (And FYI, this can actually happen in other parts of the calendar year, not just the end.)

[mdavidn]

A leap second would be a change "less than 3 hours," so the job should still run according to the cited Debian man page.

Google's NTP servers smear leap seconds over an entire day, so UTC may appear continuous despite leap seconds.

https://developers.google.com/time/smear

[tshaddox]

Indeed. I only meant that simply switching to UTC doesn't actually reduce the necessity for the complex handling of scheduled events this article describes. It would just make these cases occur less frequently.