He used all 3 last time he cut Kaido and Zoro does switch between his blades there is zero proof Enma is the only sword he has been this whole time. Trying too hard to turn him into 1 swordstyle fighter which will never happen Enma won't change the style he developed and been using since...
He did cut Kiado wiith all 3 swords and why would Zoro suddenly turn into a 1 swords style swordsman when we know he is at his best when he uses all 3. Some people are too damn desperate to drag Zoro down at any cost
Zoro was over restricting Enma that is why he wanted to loosen that up despite the risks involved with it they were dealing with two yonkos after all, there is nothing more to it than that we had almost whole chapter dedicated to how this sword works
See how bad that sound when you use that logic and the funny thing is Enma is far more inferior to a df that alters your whole body, the sword doesn't add anything more than he had with Shusui in addition it comes with the nerf of draining his haki while getting fully used to it