I talked about the major scenes because they are driven by the major choices of the game.
They are driven mostly by a binary "Yes / No" flag for their relationship, with additional flags to include deviations such as Ian perving on Alison x Jeremy. That's easy to track. What is NOT easy to track however is the dialogues. If you really want to compare complexity of each chapter, you'd have to compare the amount of dialogue. And the fight with Robert in the gallery was 200% more complex than any sex scene development. Sex scenes tend to be very linear in nature, with most of the branches impacting the dialogue that leads to said sex scenes but is not that important during the scene itself.
There's no dialogue in Chapter 6 that would compare to the date with Lena in Chapter 9 in its complexity. The most complex scene in Chapter 6 was hanging out with Holly and Ivy / Louise and it only depended on holly_gym variable.
Why would it be a nightmare to keep track of things ? Especially when you have the previous experience of doing exactly this.
2 protagonists. NPC characters have agency, develop off-screen and interact with each other. In GGGB nobody interacted with each other unless Ash brought them together. Eva is the only exception to that rule, being the mirror to Ashley. So, if in GGGB Eva could forget about side characters entirely if they were not featured in the update, this time, even if they're not present in the chapter, Eva still has to think of something that they're doing at the time they're not present. How have Cindy and Axel's photoshoots progressed if Ian didn't come along and Lena didn't come to make him finish early?
And finally, about "Decisions from chapter 2 not impacting content in chapter 9". Blocking Jeremy's advances for Alison in Chapter 3 ("Alison is only mine") prevents him from ever raising the threesome topic to Ian. So, there are no clear rules of whether some "minor" dialogue choices can end up being not really minor. Hell, Lena can bring up the fact that Ian showed her Peoplegram to Jeremy if he complains about her sexting with him, daring him to face this weird inner conflict of why he was okay to show her off to him (and potentially discovering her Stalkfap thanks to that gesture which is only different from sexting based on interaction). So, in theory, we have one seemingly random decision coupled with Ian dating Lena and Lena's Stalkfap content potentially opening a door for Ian's cuck route with Lena. But that depends on whether Eva remembers that small choice or not.
