Partial ticks: haste does not make waste
Before 6.0.2, adding Haste would reduce the duration of a HoT/DoT by increasing the frequency of the ticks, until finally a “breakpoint” was reached that would reset the ability to its full duration by squeezing an additional tick in at the end. This was a major factor in the gameplay for DoT-based DPS classes.
Now, after 6.0.2, that whole angle is gone. Instead of the duration of the ability changing depending on your Haste, it will always last the duration that’s stamped on the box. As you add Haste the frequency of the ticks will still speed up and, because there will be empty space at the end after that last tick, when the ability runs its course there will be a “partial tick” at the very end that fires for an amount based on how much time was left in the ability duration after the last full tick.
So what all this means for us: Sacred Shield and Eternal Flame will always last 30 seconds, and if we let them fall off, we will not have wasted “dead space” at the end but instead have some kind of compensation for anything after the last full tick.
That said, there’s no reason to let the abilities fall off if you can help it, because …
All classes have now caught the Pandemic
The now-removed Warlock passive Pandemic allowed them to refresh their DoTs early and tack on 50% of the ability’s remaining duration when it was refreshed. In 6.0.2 this benefit was given to all HoTs and DoTs across all classes as a baseline mechanic, and the percentage was reduced to 30%. (And it is awesome.)
For us this means that if you refresh Sacred Shield or Eternal Flame before it runs out (which you can do so to avoid a partial tick) you will have extra time tacked onto the end of the new duration. This makes it a little easier to find the right moment to refresh those crucial abilities, and doesn’t penalize you if you have to refresh them early.
Snapshotting is gone
Especially with regards to Vengeance, it was important prior to 6.0.2 to try to maximize the use of the snapshotting mechanic to get the most out of your HoTs. For example, with Eternal Flame, the best time to refresh was not just when you had 5 stacks of Bastion of Glory but also when your Vengeance was high enough that the heal would be as strong as possible. The value of maximizing use of snapshotting was so high that, for example, Theck made a “stoplight” weakaura to highlight when the optimal time to refresh EF was. Other classes were similarly dependent on maximizing this edge.
6.0.2 has removed snapshotting entirely for us; now Sacred Shield and Eternal Flame will dynamically update each tick amount for your current stats depending on procs, buffs, and so on.
For a much more detailed look at these mechanic changes, check out this post from Hamlet.