Up to that - new knowledge and improvements are coming all the time - look at the development of A330 so I do not believe the rework phase would ever vanish. There might be periods when it is smaller and it might be later bigger etc.
The A330 from the period of MSN 200 is dramatically different to the one with MSN around 500 and even more around 1000 and much more around now.......
This is an entirely different topic. - Rework on early frames is a consequence of early improvements following flight test findings. - 'Traveled work' - per Boeing parlance - is a consequence of an increasing assembly pace : aircraft are moved on to the next station even when some items are still missing. - Design improvements can be implemented even on mature aircraft to keep them competitive (for instance, Boeing now sells an improved 77W, hoping to spur enough sales to keep the line going at the same pace until 777X production starts). Production however is performed per plans.
I agree with Baroque, most probably the tents now are used to perform work that was left out for lack of time in the assembly process. Strictly speaking, it's no 'traveled work' since everything in this case takes place in the same factory (work does not 'travel'), whereas Boeing coined the term when they had unfinished fuselage sections shipped to the FAL and completed there.