It either that it would one shot ulti and it's too strong, and Oda is restricting it for that reason
We know Gear 4 consumes more haki than his base form. Advanced Armament Haki is more effecient than Regular Gear 4.
Either Luffy has fully mastered it, which is why he is not using it.
We see Zoro using Enma Practicing with it on live Opponents, so Luffy not using it on live opponents such as Uti and Page one makes no logical sense.
Unless he has fully mastered it completely and it is far far stronger than we think.
We know Gear 4 consumes more haki than his base form. Advanced Armament Haki is more effecient than Regular Gear 4.
Either Luffy has fully mastered it, which is why he is not using it.
We see Zoro using Enma Practicing with it on live Opponents, so Luffy not using it on live opponents such as Uti and Page one makes no logical sense.
Unless he has fully mastered it completely and it is far far stronger than we think.