I feel like just posting every day in which duties I get stuttering or don't as I randomly do them. Note this is only ever when fighting, and I got absolutely zero stuttering before 6.0.1.
Today:
Titan Hard: None at all.
Second dungeon of Endwalker: None all the way until the area immediately before second boss (the "centipedes"). Then, again at second boss but only once bombs explode and for a little bit after. Still again all throughout last area. However, none at all through the last boss.
Syrcus Tower: None until after first boss, then always can crop up in varying degrees of severity.
Alexander - The Arm of the Father: All through the first area. However, none at boss.
Smileton: All the way through with considerably varying degrees of severity. Sometimes, it seemed to really depend on where in the background I was looking at.
The Stigma Dreamscape: Present in the very first area, then only in the last area before last boss.
Another issue that I didn't realize until doing old duties for the first time since 6.0: The sound balance is messed up, let alone the bass and other players' volume. It's particularly noticeable with Ambient Sounds in Arm of the Father for the electrified water. What's funny is that my computer is very old, yet actually suffering far less than people with much newer computers, so just getting a new computer isn't really an answer. For reference, my GPU is GeForce GTX 970 and CPU is i7 920 2.67 GHz, and I'm on a hard drive. Yeah, that's how old, yet still doing a lot better than people with modern computers and had zero problems before Endwalker.
Just why. Why ruin your game for...what, a silly collaboration with Embody, the entity that pushed this utterly ruinous Spatial Audio on us? It was all perfect before. It didn't need any "improvement" to make Endwalker as good as it was. I'm just so lucky I was able to finish just before the patch.