My Helix spells cap at 19 damage on the rocks, and that's regardless of weather/day bonuses. That's the only DoT Scholar actually gets. The other DoT's are from your support job, which means going with either Black Mage or Red Mage. Elemental DoT's don't seem to do much damage per tick, so it's a fair bet those are also reduced in effectiveness also. All weapon strikes cap at 19 damage on a critical, with +2 for enchantments if I go /RDM.
Each rock has upwards of 2k hp, so to do the math each rock basically takes 6 minutes to whittle down by pure melee alone (6x5 = 30 mins, out of time). Being generous, that can be reduced to about 5 minutes with DoT. That's still 25 minutes already taken up, and I haven't even considered travel time.
The Qiqirn Bombs would be helpful, but they don't drop often, and equipping /THF means no DoT besides my Helix spells to work on the rocks. Maybe tier 2 helix spells work wonders, but I've got a long way to go before I get that many job points and my highest gear is only level 117.
