Hours belong to the person you are calling
Permitted calling hours are set where the contact is, not where you are. A campaign timed against your own clock will reach some people early and others late, and both are breaches even when the intent was fine.
Time zones make this worse than it sounds. Regions split across several zones, and not all of them move for daylight saving. The offset you assumed in one month is wrong in the next.
The holiday problem
There is rarely a single holiday calendar that covers a whole country. States and regions keep their own days, and a campaign configured weeks earlier does not know about them unless something tells it.
This is how a sequence built on a Friday ends up dialling someone on a regional public holiday the following week. Nobody decided to do it. The schedule simply was not aware.
Why per call is the part that hurts
Calling breaches are usually counted per call, and that changes the arithmetic completely.
A schedule that ignores local hours is not one mistake. It is one mistake repeated once for every number it dials.
Teams tend to price this risk like a fixed fine, absorbed and forgotten. Counted per call, a single careless campaign is a different order of exposure, and it grows with your volume rather than staying flat.
What to automate
The fix is not vigilance, it is scheduling that knows three things: the contact's time zone, the right calling window for their region including daylight saving, and the regional holiday calendar. Add a recorded sign off before launch and the common breaches simply stop happening.
Sellora applies calling windows in each contact's local time and skips the days it should. The point is that the schedule carries the rules, so a person does not have to remember them mid campaign.
This is a practical summary for sales and operations teams, not legal advice. Rules vary by market and change over time, so confirm the current requirements for the regions you sell into.