Can it be a bit of both? Trying to get a everyone to pull in the same direction when more than half of them are in another time zone is such an uphill battle. Even smaller things like trying to resolve CR feedback in a reasonable amount of time becomes a herculean effort when you only overlap for about an hour each day, and all other communication falls into a "We'll see what they say tomorrow" bucket.

Returning to a team that was all (more or less) in the same time zone has been amazing for my sanity.