Luffy realized he has CoC during Time-Skip, Zoro didn't
Zoro learned Barrier CoA (Basically to release your CoA, rather than just Focus it) during Time-Skip, Luffy didn't
So in the Battle after Luffy learned Barrier CoA, he Unlocked CoC Coating
While Zoro Unlocked CoC Coating, in the Battle after he learned he has CoC
However even though this doesn't prove anyone's Superiority, as they were simply in need of more Experience
We need to realize that knowing about Barrier CoA & CoC is still not enough to learn CoC Coating
As seen by Katakuri who is way more Experienced & his CoA is really Strong & he is Son of Big Mom & yet didn't achieve CoC Coating
Imo people should stop using that SBS Question about Haki Specialization
It only indicates which Type is easier for them to Learn but Luffy & Zoro are clearly meant to be Masters of All Three Haki Types
Followed by Sanji, Jinbe & Usopp who each specialize in a Haki Type (CoO, CoA & CoC Respectively)
I expect EOS, we are gonna see a Legendary CoO Feat from Sanji, a Legendary CoA Feat from Jinbe & a Legendary CoC Feat from Usopp
(For Usopp, simply Unlocking it in a very Crucial Moment will be Epic enough & unprecedented for such a Weak/Coward Character)
While Luffy & Zoro are gonna become the Ultimate Haki Masters
For example, we've seen Gear 4 & KOH which exhausts all their CoA resulting in a Temporary Powerful Form
It's possible that Gear 5 & Asura also exhaust all their CoC & are also Temporary
So maybe CoO can also be Exhausted for a Temporary Insane Reflexes Upgrade (Maybe it's related to Zoro's Left Eye)
Also in One Piece Games, we've seen Shanks Slow Time so maybe that's what Fully using your CoO results in, which makes Total Sense
Maybe Luffy's & Zoro's Final Power is a Form that Exhausts all their Three Haki Types
What's really interesting though is that when Luffy used Gear 4, both Doffy & Kaidou found it strange as if Luffy was Half-Awakened
And then Gear 5 turned out to be Luffy's DF Awakening, Oda is clearly creating a Parallel between Haki Full Usage & DF Awakening
And conveniently we have Three DF Types, where one gives you Dominance over Nature, one gives you Physical Upgrade & one is basically like turning Imagination into Reality. It seems that DFs were created from Haki, a very Powerful Source where it's CoA was used to create Zoans, it's CoO was used to create Paramecia & it's CoC was used to create Logia
It's clear to me that DFs are associated with Sea Devil cuz they indeed come from the Sea
In other Words, the Sea itself has a "Will" & hence "Haki" & Sea Devil is apparently it's Personification
It's CoO, CoA & CoC were used to create Devil Fruits, that's why Users are unable to move in the Sea, it's cuz that's their Powers Original Source, their Will is strengthened there rendering the User unable to regain Control over their own Body
The reason i'm explaining DFs now is only to shed light on the Sea Devil & how it's Haki is what shaped this Story or at least some of it
And that apparently, Luffy & Zoro are meant to have Haki on the Level of this Sea Devil & just like the later gave birth to Three DF Types
Luffy & Zoro will also use their Three Haki Types to Forge "Three Key Items"
Zoro already got his Three Swords, it's clear that one will claim Zoro's CoA turning it into a Black Blade
One will claim Zoro's CoO turning it into a Flaming Sword
Third one will claim Zoro's CoC turning into an Unknown Type of Sword but some Hints indicate a Red Sword
As for Luffy, he obviously needs to use his Haki Types to also Awaken Three Keys
They need to be Super Major Items that are extremely important for entire Story, entire World & everyone he knows
In my opinion, it's clearly The Sun, The Moon & Earth itself
The Sun will claim Luffy's CoC
The Moon will claim Luffy's CoA
The Earth will claim Luffy's CoO
There is big Chance that Luffy & Zoro aren't meant to live after Final Arc (Personally i wish entire Crew dies, just like Brook's Flashback, but instead of Painful Death, it's actually a Happy Ending)
Oda is already flirting with the idea of them dying multiple times
And i find it interesting that he already prepared New Owners for Zoro's Swords
Such as Enma which should belong to Momo or Wano in General
And Tashigi who promised to take Kuina's Sword or the one he bought in Loguetown
Anyway, these were just some Fun Theory Additions
My Answer to this Thread is that simply both Luffy & Zoro are Specialized in All Haki Types cuz they are meant to use them EOS to achieve their Dreams (Which has World Changing Consequences). However, the same applies to other SHs Roles & Dreams, i simply mentioned the Duo discussed in this Thread.