I'd like to follow up on this problem.
So I just bought a new axon7 which has native daydream support. But since I don't have a daydream helmet so I still use this phone in the cardboard way.
Now wierd things is that, for the same video , I feel very comfortable with the default slider config. I mean, the IPD doesn't feel too small and I do have vivid 3D feellings.
The old phone mentioned earlier is Redmi Note 3. Both phone are 5.5inch, lineage OS configured with the same cardboard profile(Mi vr play2). The only difference would be the resolution: the old is 1080p and the new is 1440p.
So could you maybe provide some theory why the two don't offer same experience?