Suggestion to devs to replace DoT timers.

[Zfz]

So it boils down to managing DoTs correctly. In summary, all DoTs (duration/3) ticks.

Let me try and find out exactly what the problem may be. Please do point out any mistakes I make.

Each dash(-) is 0.5 second without the DoT debuff, each plus(+) is a potential tick at the instant.
Each pipe(|) is application of the DoT at that instant, and star(*) means the DoT falling off at that instant.

Suppose our DoT lasts for 6 seconds (2 ticks). For a 15 second duration:

No DoT
----+------+------+------+------+--

Various cases of apply and let it fall off, reapply in 0.5 seconds.
--|--+------+----*-|-+------+-----*-+--
---|-+------+-----*-|+------+------*+--
----|+------+------*+-|-----+------+-*-
Note that in the third case, there's one potential tick you miss out simply because it fell between your DoT applications.

Various cases of reapplying 0.5 seconds before it falls off.
|----+------+-|-----+------+|------+--
-|---+------+--|----+------+-|-----+--
--|--+------+---|---+------+--|----+--
---|-+------+----|--+------+---|---+--
----|+------+-----|-+------+----|--+--
----+|------+------|+------+-----|-+--
----+-|-----+------+|------+------|+--
You'll realize that in the last case, the second duration of the debuff got only 1 tick.

Now look at the first case of the early reapplication. The reapplication could actually be delayed for 2 seconds without missing any ticks.
The closer your first application was to the previous tick time, the more you could space out your next reapplication.

So let's look now at a 1 minute period utilizing the delay tactic for 1.5 seconds, mixed with the 0.5 second early reapplication:
|----+------+--*---|-+------+----|--+------+---|---+------+--|----+------+--*
---|-+------+----|--+------+---|---+------+--|----+------+--*---|-+------+--
And you should see the pattern here.

We let it fell off 3 times, earning 4.5 seconds time we could use on other things.
For example, that 1.5 seconds could let us complete a Ruin cast.
This is a peculiar result of the system where ticks are not dependent on the debuff duration.

Personally I'd prefer that this peculiarity be resolved on the server side by allowing some extension of debuff time.