Experience from Monk

[Sigred]

Sometimes it's really usefull when you know the boss is going to go away for a while so you can put your dots on him before.

Why do people still think that this is a thing? That's not how it works. Just because a DoT might still be applying damage while you are physically incapable of using further attacks on an enemy does not magically make them do more damage than if you were to use the same GCD (that you used to apply the DoT with) for any other attack instead.

Whether you have to disconnect from an enemy for *any* duration of time (as a generic rule) has absolutely no effect on the damage done by any particular ability in relation to how those abilities perform for a given interval. The only parameter that has any meaningful data for comparing the damage of one ability to another is within the interval of effective potency by GCD. That is to say, the only meaningful statistic is the total potency that will result from the action of utilizing a singular GCD in order to utilize/apply the ability.

If you have a DoT ability that does 200 potency over the course of its duration, and a direct damage ability that also does 200 potency, then there is absolutely no difference between spending a single GCD to use either ability. It does not matter how any further GCDs from that single window are utilized. You spent one GCD to use an ability, and that single GCD returns an expected total potency. You could use either ability then go sit on your hands for 30 seconds, and the returned value from that GCD wouldn't have changed at all.

Now since DoTs do generally have a higher total potency if they run their full course uninterrupted, you would generally put the application of a DoT ability ahead of others in a priority rotation. However, because of the previously described rule, the only factor that can alter the effective potency of the GCD utilized to apply a DoT is causing the full course of the DoT to be interrupted. This can happen by reapplying a DoT before the original has finished, from forced boss transitions, or from the mob dying before the DoT has finished (negligible at that point). Either or both of the first two means that you have effectively devalued the output of the GCD used to originally apply the DoT; thus, making it less effective than if you had just hit a direct damage ability instead.

Since the most common situation that you'll be forced to spend time away from a boss is primal phase transitions, and they go invulnerable when transitioning (even though DoTs are still ticking for 0 damage), trying to put a DoT on just because you have to disconnect is actually about the worst thing you could do.

TL;DR

Stay in school and learn math.