Top DPS in you t5 clearing groups?

[EasymodeX]

Hmm, Fire III, 3x Fire II, Flare, Convert/SC Flare, Mana pot Flare bringing them to 40% or less in 20 seconds and then switching to ST Cad feels fairly efficient to me

That's not how you measure efficiency.

Efficiency is a Summoner pressing 1 button (sidenote: ok they'd probably press 3) for the same effect over your 3x meh DPS Fire 2s that you spent close to ten seconds casting and 2x slowcast Flares which cost you another what, 7s or so? SC Flare is efficient. You could have dealt 10k more damage to Aslecpius in that time if you used a ST rotation.

BLMs have solid ST DPS, and great AOE DPS.

BLMs have bad multi-target DPS. Three targets = multi-target DPS. 2-3 targets is the worst DPS profile for a BLM, aside from their burst contribution from an SC Flare. Min-maxing means losing the least amount of single target Asclepius damage in order to achieve the necessary damage on the small snakes.

The only reason BLMs are commonly used for snake pounding is because they have "no resource pool" and because SMNs are uncommon -- with a side of an SC Flare actually being "free", efficient AOE DPS.

As a result their AOE does not detract from their ST DPS elsewhere in the fight. If you ignored TP, then in a generic group maximum snake phase DPS would involve tab-DoTing by the Bard, Dragoon, and Monk (assuming you have no SMN), with the BLM using 99% single target on Asclepius while throwing in the aforementioned SC Flare. There's also probably something you could efficiently work in with 1 AOE Ice spell during UI, but I'm not smart enough on detailed BLM mechanics to say what (edit: and it would probably require Spell Speed itemization). The BLM could probably also tab-Thunder the small snakes actually. You could probably rack up a ton of TC procs.