From the work I have seen, it has required quite a lot of cable manipulations, with the cable often not being one a set of supports, one reason it probably hasn't been as quick is because the can't move the cable without clearing the ground of people.I don't believe that is the quickest it can be done, no. Many hands make light work.
I'm not pretending to have any industry specific knowledge, are you?
This means they have had to work on it over night often, if the were to do work during the day the probably would have had to close areas like dark forest so they can work on it (there is no way to get to 13 or rita without going under the cable)