You're counting the third modus twice, to the tenth power in that equation.
2 ^ 10 = 1024
194560 / 1024 = 190
If you pulled 194560 with 9 SCH:
2 ^ 9 = 512
194560 / 512 = 380 damage Helix would be needed.
That's the incredibly easy part. It sounds great on paper but it's difficult in practice. Modus Veritas used by 9 SCH on a Helix reduces it's duration to 3.4 ~ 6.7 seconds. Like you said, because of the merits.
Since Helix duration is apparently random, that also leads to more possibilities of error, both from the small window of time for human error and lag from a connection. The milliseconds really add up. The main reason it's difficult is finding precisely when the "tick" occurs.