Recent reports have minimized the role the recent work has played in the post-production process, however, suggesting that Whedon's task in bringing Justice League to the big screen is simply to touch up what Snyder already shot. Journalist Mark Hughes has a nice summation of the situation as it stands:
"As of right now, despite the fact that there's been some extended time and it's like 'ok, if this is still ... why are they still doing shoots on this,' there's been a lot of downtime in between shooting because of people's schedules; they have not been shooting this entire time. The amount of content that has been shot and is being shot is still pretty much what they expected and figured was going to be happening. They haven't said 'oh, we need to add additional, we need to do a whole bunch more,' or anything like that at this point, so, the footage and the amount of footage in the film, as of right now, the majority of the footage that you're going to see on the screen is still the footage that was previously shot during principal photography."