how does 5 scene advance all at once instaed of 1 scene becoming more complete? And doesn't some scene already start with some completion, after all there are scenes that are continuations to one another, and have the same renders as the previous ones in the beginning of that/those scene/s? Sorry if it was already answered.
If I did everything serially, I'd be waiting all the time to finish up rendering, which is a huge waste of time. There's quite a few tasks involved; writing dialog, creating scenes for rendering, post processing finished images, script transforms, edit, rework and fix, etc. All except for the scenes creation can go parallel to rendering, and scenes creation is by far the biggest time sink, so in the end it comes down to making sure there's always something to render while I'm doing one of the other jobs, and always having some other job laying around while I'm waiting for the renders to finish, and the image creation job is the tool to balance that all out. That way there's minimal downtime.
Scenes that re-use assets (like the paperdoll conversation scenes in the kitchen, living room, work, bathroom, etc.) will have just the one face because they can be wrapped up relatively quick, but they're hardly without any work at all (dialog needs to be written, the images need to be edited in, scripting the transforms, sometimes a particular emote wasn't done yet for that location/time of day/outfit and needs to be added, or the occasional special variant of an emote is needed, etc.).
Also keep in mind that not all tasks capture well in those images. That infograph was created just about 1 year ago when I finished blocking out the first draft of this chapter. Rework and expanding scope isn't really visualized there unless it's really significant, and for instance last week I did an end-to-end continuity pass that reworks and tweaks a lot of existing scenes, but doesn't show up at all on that infograph except in the hours report.