Traveling At Different Rates?

We will quote three passages from Poul Anderson's There Will Be Time and draw some conclusions.

(i) "'How long does it take? How many minutes per year, or whatever?'

"'No particular relationship. Depends on me. I feel the effort I'm exerting, and can gauge it roughly. I can move...faster...than otherwise.'" (IV, p. 37)

(ii) Two Eyrie agents hold Havig, their prisoner, as they travel uptime:

"They had substance to his senses, like his own body..." (XII, p. 133)

(iii) In Jerusalem, one Eyrie agent leads a group from the day of the Crucifixion to the twenty-first century. They stop when they see:

"...a kind of big billboard in the ruins, on which an indicator was set daily to the correct date." (VI, p. 64)

The group in Jerusalem depart together. If they stand close enough, then they continue to see each other while time traveling. Presumably they stop together immediately after midnight when they see their destination date appear on the billboard. But they will probably "travel" at different rates. Does it follow from this that one, maybe the leader, will get ahead of the others, will then lose sight of them while traveling and will arrive at 00:00 hours before any of others? No. One person cannot be at 00:00 before another. They must both be at 00:00 at 00:00. We must not think of the two millennia between the day of the Crucifixion and the twenty-first century as if they were a spatial distance with a number of three-dimensional bodies moving along it. The world lines of the time travelers extend from 33 A.D. to 2033 A.D. (or whichever year in the twenty-first century we are talking about). Each of the time travelers will be visible to all of the others throughout that period. The difference is that the one who "travels" faster experiences, e.g., one second per century whereas another who "travels" more slowly experiences maybe two seconds per century. They are not really traveling anywhere and the language of time travel becomes confusing. In other sf works, this situation is called temporal stasis.