So most of your points are very good, but there are two major things resulting from the following quote that are massively wrong
Do you kill the first Shade of Orobyss do you encounter or do you go far out in the Timeline and try killing one with +14, +16 or +18 Corruption?
The deeper the Shade of Orobyss, the higher the drop chances for its rare items.
On top of that, farming Shade of Orobyss is counter-productive to farming Unique/Set Echoes and Timeline Bosses, because Shade of Orobyss will reset the timeline, but the most effecient way to farm a timeline is to keep a very developed timeline.
Because the chance for rare echo rewards (Such as Unique/Set Body Armor) is massively higher for deeper echoes and if you constantly reset the timeline you always sepnt a lot of time in the very shallow part of the Timeline.
On top fo that the deeper echoes give massively more Stability, meaning you need over half as much echoes to completely fill the Stability needed for a Timeline Boss.
So even if Shattered Chains is a desired Item, I would not recommend killing Shades too often. When the alternative would be way more consitent and reliable last Step of the Living and Exsanguinous chances.
On top of that, if you have really really developed timelines and you do encounter a Vessel of Memory or Vessel of Chaos these are exponentially more valueable, the more echoes you have uncovered.
Here is a advanced guide on how to maximize your Vessels:
At the end of the day RNG is RNG and sometimes you are lucky sometimes you are not.
But over a long enough timeframe you can mitigate the worst RNG for the most part.
I have farmed 2-3LP Titan Hearts on multipel characters over the last few patches (even before 1.0 and CoF exsited) and because it is also a Uniqe Body Armour the strategy and timeline is the same for Exsanguinous.
While farming Titan Hearts I found dozens, if not hundreds of 2LP Exsanguinous.
Titan Heart is more common than Exsanguinous, but has significantly lower LP chance.
I don’t want to downplay your bad experience with the game systems, but I can assure you, you can reliably get 2LP Exsanguinous even with bad RNG within a few dozen hours of playtime.