Yea I know that narrative and the memes to lead the opposing arguments ab absurdum, but I don't buy into it.
In my view Oda differenciates between scuffles and fights fights.
And in real fights he was (never) inconsistent.
You have to take into account the thousand times where he draws the visuals, most of the time even right before or after those questionable "inconsistent" feats.
Nah he's simply dropping characters' IQ points from time to time and that's just it, for whatever reasons: avoiding of spoilers, dramatic purposes etc.
Using aCoC on Egghead against the Gorosei would have spoiled its effectivness f.e.
And here with Luffy we even have it on panel, as he's physically touching the shield, when one of his biggest main PUs a while back does the opposite.
Oda just works like that. Same guy that silhouettes hybrids for years later to show afterall.