Very rare indeed lol :P
And I'm home from the office now and read my old posts/notes about it, it was the other way around (just like you described).
It was ONE SCHOLAR using Helix on a target, and all the other 17 Scholars in the alliance using Modus Veritas at the same exact time. That was making the next tic insanely powerful etc.
It got nerfed, altough honestly that strategy required so much coordination (we were talking about real second by second syncronization among players from very different areas and with very different latencies...) that I wouldn't really consider it as something easily useable in most circumstances.
True.But back to the healing helix, having multiple people stack HOTs to keep someone alive should be the point, not seen as an abuse. Right now one white mage with some refresh support can do this with direct cure spells, if HOTs can't provide the same amount of utility they they will be passed over for what works.
Altough in this picture you'd be able to stack Soothing Helix and Regen, but anyway in my view I didn't consider Soothing Helix as something to use in place of cures, but rather something complementary, to use in synergy with them to create a new interesting and original way of providing a decent way of healing (altough not as strong as a WHM, of course). You'd be able to place HoTs strategically anticipating damage phases, and then topping people off with cures as you would do normally, difference is that HotS would be active (requiring less cures) and your cures would be more effective).
It's a very common way of healing in other MMORPGs, but in FFXI we just have the WHM model, copied in a more gimp way by RDM, SCH and possibly other jobs subbing /WHM.