Castsequence macros are full of holes!

[SmartJelly]

Based on my personal observations...

When I cast (spam button) using a cast sequence, eg

/castsequence Wrath

..the cast bar pops appears, fills all the way to the right, turns green and flashes then fades away. Only then is the next cast started. If it's an instant cast spell then there's no cast bar and the next cast starts after the global cooldown is over.

When I cast without a sequence, eg:

/cast Wrath

..the cast bar doesn't always reach the end before starting the next cast (there is no change to green, flash or fade) and the time between casts decreases (increasing dps).

As the OP noticed, and some may already know, a macro such as:

/castsequence wibble
/cast wobble

..will drop down to the wobble spell after casting wibble (if wibble isn't instant and you start/click/press/spam the macro at the right time).

Additionally, casting wobble will also cut short the cast bar animation of Wibble in the same way as observed with /cast Wrath above (but only is wobble isn't instant). Wobble will in turn be cut short by Wibble.

Because Wrath and Starfire are neither instant or have a cooldown, there would be no benefit (other than personal preference/size/etc) in using /click instead of the following:

/castsequence Starfire
/castsequence Wrath

Indeed, one could extend this with no loss due to castsequence delays:

/castsequence [target=focustarget] Starfire
/castsequence [target=focustarget] Insect Swarm, Moonfire, Wrath, Wrath, Wrath

(edit: this isn't right as there'd be a delay between SF, IS and also SF,MF)

However, if the next spell on the 2nd line has a cooldown then casting will continue with the 1st line sequence and be subject to delay. Thus:

/castsequence Lightning Bolt
/castsequence Flame Shock, Lava Burst

..will be delayed between concurrent LB casts until Lava Burst is off cooldown (Flame Shock is instant so doesn't help with delay).

Note: A cast will never be cut short if it's followed by an instant cast, using /click, /cast, manual casting, or whatever.

The /click method (or more specifically the use of additional commas) can be used to rejig macros such that they suffer less from cast sequence delays, but it's still obeys the rules/observations stated above, and it all works off the bug/feature mentioned by the OP.

[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.