First you have to have all the assets, then build the sets. Cloth the characters. Place everything down. Pose the characters and then animate them. That, alone, will take a month, or so, for an entire episode's worth of content. Considering Ocean likes flippy floppy hair (which I am going to assume is rendered at 30fps for a 5 second loop) that is 150 rendered frames for one single scene. Now say there are 30 scenes, just simple flippy floppy hair, going into one chapter - That is 4,500 rendered images. Add 3k stills and all the other rendered images belonging to other animations, you might be looking at 10k-15k rendered images. Taking the 15k number and, say, using a single 4090. That would take 5-6 days if you rendered everything there and then, back to back.
However it will still take you many weeks to get everything in position and ready. Of course there is all the post processing stuff to do as well. So, by and large, doing the visuals of an AVN can take a big ol' chunk out of the dev time cycle.