Machinist superior then bards?

[JohnMccain]

Which tooltip is relevant and proves your point?

http://xivdb.com/?skill/90055/River-of-Blood
"Grants a 50% chance that critical damage over time inflicted by Venomous Bite or Windbite will reset the Bloodletter recast timer."
I will even hold your hand and paraphrase it for you. If your VB or WB tic for critical damage, you have a 50% chance of bloodletter resetting.

DoT tics however, tic at the same time. So your VB and WB(even if both of them crit) can only reset bloodletter once every 3 seconds.
Here is a random video I found on youtube demonstrating that: https://www.youtube.com/watch?v=0ZnpeVTbVGE
The only time there are two DoT tics not ticing simultaneously is if there is flaming arrow and WB/VB going.