Time flows independently in every Hex.
A Unit moving from one hex to another will experience a shift in time when moving between hexes, but only if the unit has been observed. Otherwise, as no paradoxes would be caused, the time of the new hex would adjust to your time.Erf-b1.5-p029
While length of time is relative, the order of events is absolute. If there are events A, B, and C being observed from two different hexes. Hex one may say: A took 15 minutes, then B took 10, then C took 20. Hex two may say A took 5, then B took 30, then C took 15. In all cases everyone would agree that A happened, then B happened, then C happened.
It's best to try not to think too hard about this.
The Scout's Paradox
This flow of time may be necessary to allow for true Turn based causality to exist.
Suppose a commander ordered a scout to use half its movement traveling west, then return. The scout does so and reports that nothing was found. Based on that result the commander sends a scout to do the same for the south. This repeats two more times. From each scout's perspective six hours passed on their personal trip.
If time is absolute this whole process would require at least 24 hours as we can't send a new scout out until we know what the first one found.
With ErfWolrd time the six hours a scout spends in the field may be only 30 minutes to those in the home city. Each scout expends a whole day's effort while the commander is able to get all his scouting done in 2 hours from his perspective.