Castsequence macros are full of holes!

[Coyote]

Actually, the commas are mostly used for timing.

As you noted,
/castsequence Lightning Bolt
/castsequence Flame Shock, Lava Burst
Will drop down to the second line if you hit the macro the moment your cast is finished on the server but still not finished in the client.

However, this has little practical value in most dps rotations.

As an elemental shaman, my ideal rotation is to Flame Shock every 18 seconds to refresh the dot, Lava Burst every time its off cooldown (8 seconds), and fill the void with Lightning Bolts (ignoring Chain Lightning for the moment).

If I make a macro with "/castsequence Flame Shock" followed by 17 commas, and I press it exactly once every second, the net effect is that Flame Shock is cast every 18 seconds as desired. Furthermore, the 17 clicks after each Flame Shock are not consumed, but will 'fall through' and be able to initiate spells further down the macro. As an added bonus, the latency loss of concurrent spells in the same cast sequence is avoided. And it is haste proof to boot.

The ability to time how frequently every spell in your rotation is cast (for any value of haste and heroism), in combination with avoiding the latency hit classic /castsequences suffer, is what gives the concurrent castsequence method it's strength. But it requires a fairly consistent rate of button presses, something I am sorely deficient at

[SmartJelly]

However, this has little practical value in most dps rotations.

As an elemental shaman, my ideal rotation is...

I was not trying to offer advice on rotations, I was trying to describe the mechanics of the effect described in the original post and its relationship to castsequence delays.

I would agree that comma sequences are one of the tools at our disposal for improving macros.