Well with Reverbation we can shock every 5 seconds, or 6 seconds without this talent.

We can Flame Shock one target and then Flame Shock a second target.
Then Lava Burst either target and follow that up with an instant cast Earth Shock.

It is not optimal, because they can decurse our Flame Shock which then removes the auto-crit on the following Lava Burst.

Alternatively, you can rely on Flame Shock - Lava Burst - Earth Shock - Lightning Stuff to be more burst then they can heal through, even knowing it is coming.
The drawback will be immunity effects such as Bubble or perhaps Pain Suppression on the target for half damage.