What you’re calling “attention span” is probably more accurately called “user expectations”, or “user patience” which, obviously, can easily change. On the oth

What you’re calling “attention span” is probably more accurately called “user expectations”, or “user patience” which, obviously, can easily change. On the other hand, there seems to be a measurably consistent maximum amount of time that one can tolerate a pause without also breaking out of flow. This might be cultural, but it seems to be consistent enough that it could be physiological.