I have a vague memory that my (matcha) tea sensei once told me it's more correct to hold a kyuusu using the two-handed approach, with one hand gripping the handle while the other holds the lid in place.
On the other hand, it could be a hallucination brought on by drinking too much tea
Given the efficiency of the Japanese, I suspect you were hallucinating!
I mean think of all the things you could be doing with your free hand while pouring. Cooking supper, doing a report, ironing...
Actually, I found out the hard way, you still need to focus when pouring with one hand, no multi tasking. I have 2 chipped spouts, no make that 3, as a result of minor bumps while not paying complete
attention to pouring. Clay tips chip easily it seems.
I guess there is "proper" and there is "common practice" which could be in conflict. I don't care as long as everyone is aligning the hole with the spout!!!!!!!! That's the important thing.