That's pretty accurate! Sometimes the step crumbles before our hero gets to the next one. Sometimes the next step is missing completely.
Fortunately there is a safety net at the bottom, and a less crumbly but slower staircase available.
But actually operations that require a sequence count change are not so common, and path walks require sequence protection only briefly, so sequence count failure is quite rare. It's more common that the dentry is missing or some filesystem operation requires blocking, which can be handled more gracefully.