For my range (skills around 130s), I've noticed that multi-stike TM is seriously beating out weapons with every critter I can withstand at melee. Tm is 132 with disc 25, wis 24, int 22; and polearms is 135 with 26 str, 24 agi. I've been to serpents, gargs (even though they're really easy, weapons still take a while to kill them), swamp trolls, and I just did a test with day-time bargs:

Using my camb halberd (135), it took 18 attacks for a total of 80 seconds using jabs, thrusts, and slices.

Using min prep fire shards, it only took 4 casts (for a total of about 40 seconds) to bring one down. With 10 prep and 10 cambrinth it only took 3 (also had similar results with STS). This part I repeated a few times because it was so quick.

Air lash was an entirely different story, it took 10 min prep hits to bring one down. Ran out of attunement for the 20 mana test.

While that seems like very few casts, I also presume at that level the armor on the monsters is not significant and that multi strike spells are ideal against lightly armored or heavily penalized enemies.