Why would you assume it does 0 damage just because it doesn't show up in the log? Tests on Batraal and deepvoid showed that the Bloodletter DoT did significant damage.
579 damage on WHISKERWALL is 100-200 more damage than bloodletter itself is doing, it requires no animation. Frankly I find your reasoning for stressing over cooldowns (once again) to be needless. Yes you want to keep everything on cooldown, but I can manage that for the most part just fine without overwriting an existing bloodletter buff. The damage from Bloodletter is good (especially on Whiskerwall) but it falls off on most moogles. So even skipping it on moogles like pomburner and pukna will make a negligible difference in your personal DPS while you can gain thousands of damage over the course of the encounter through bloodletter.
If you require proof fix your parser so that it shows bloodletter end damage in a line by itself, and try staggering to see the difference. There is no difference between now and 1.18 in regards to bloodletter. The end damage+DoT when it lands is still higher (for the most part, maybe not on many low defense moogles though but people can apply some logic on their own without having to rely on a static "rotation" in all situations) than the shot itself.
The free TP damage from Combos is nice yes. But I've proof positive through parses that you can parse similar numbers even neglecting the piercing lines completely (as an archer in my LS proved) if all you are concerned about is "overall DPS". The only time that combo damage really shows its full strength that would necessitate maybe disregarding everything else is against the high defense moogles because light shot damage falls off so quickly when calculating your attack versus their defense.
For the most part however, when you are giving advice to endgame archers the damage of the many outweighs the damage of you. You are under the assumption that somehow a five players playing a set blindered rotation (no matter how much min/max experience they have) gives you an advantage over if you would try actually coordinating your DD. People proved the fallacy of this line of thinking to you once, but yet you still cling to it.
You may not need it to beat fights, but this is a guide and you are quite frankly offering ill advice by once again offhandedly disregarding group mechanics because you personally in BG are already capable of trivializing fights without it.
Show me some actual evidence, not anecdotal garbage about "personal DPS" that it represents a significant loss by showing evidence that you cannot fire as many bloodletters during the encounter by simply staggering 20 seconds at the beginning. Because it would have to be 2-3 bloodletters to overcome the damage gained through the DoT and end bursts and unless you are purposely sabotaging your own parses that is impossible.