Hello everyone, thanks for all the useful insight, but please allow me to offer a better contextualization.

I have All the 4 combo related actions on one Cross Bar (True Thrust, Vorpal Thrust, Full Thrust, Fang and Claw). On this group I use the LifeSurge/FullThrust Macro. True Thrust here is the action itself, not a macro.
On the other Cross bar I have the other 4 combo related actions (True Thrust, Disembowel, Chaos Thrust, Wheeling Thrust). In this group I wanted to use the TrueNorth/TrueThrust Macro.

Reasons for that?
1) I noticed I was using Life Surge not even half of the times I could. Despite me having a button in a secondary action bar (which I don't use, it's there just to remind me when cooldowns are ready) there's way too many things to watch out for, and I was forgetting to use it most of the time. Plus having to swap back and forth constantly between cross bars was super annoying and was cutting away a part of my enjoyment while playing the game.
2) The same was happening pretty much with True North. Which correct me if I'm wrong but for DRG is best used for Disembowel and Chaos Thrust (and at level 80 I guess for Wheeling Thrust and Fang and Claw too, but I'm still level 74 only). I was forgetting to use it most of the time plus I was finding it super annoying to have to swap back and forth so I thought about using it in a macro, given my LifeSurge/FullThrust macro was working so well for me.


For those who said that with this setup I'm going to occasionally waste my Life Surge. Like on a monster about to die, or when I'm full HP etc.
That's absolutely true but it simply doesn't matter for me because, like I said before, I was barely using the action before, so the current situation is still miles ahead of my previous one.
Furthermore DRG is not exactely the job I'm using to make progression in grouped content. I barely do group content in general tbf, but when I do it's definitely not on DRG lol.



Edit:
What do GCD and oGCD mean?
I guess GCD is "Global CoolDown", which is the global wait there is after you execute any action. You can slightly reduce it with spell/skill haste but you can't remove it and during this time you cannot execute other actions...
...except actions which are off the global cooldown. I guess this is what oGCD means? "Off the Global CoolDown"?
Like for DRG some self buffs and jumps are oGCDs, which is exactely why I tipically use them one by one in between the actions of my combos.
Not sure that's the "correct way to play" tbf, DRG is my only melee in FFXIV, I guess it came "natural" to me from my experience in other MMORPGs before FFXIV °-°