This has been my impression as well. I feel like a lot of the basic story ideas and the general plotline had been developed way back, probably before the development even started, but most details had changed along the way. I skimmed through the earliest Patreon posts a while back, it seems like there has always been influence from the polls and fan feedback on the course of the development, even as far as the very beginning, with character designs and names. There were also some story changes influenced by how popular some of the characters were. Sam was supposed to die at the end of Part 1, for example, but this was rewritten after he became such a popular character. Some of the characters like Ayewn, Krathi, and Chad also had their roles expanded over time.
As far as the planned structure of Part 2 goes, I know that all of the primary love interests are planned to have morning shower scenes that will cover an entire week, so with the number of PLIs we have right now there should be a minimum of 6 in-game week's worth of mission content. Every other week is planned to be a filler week in terms of the main story, so that bi players will be able to catch up on all of the content, while strictly gay/straight players will just get prompts to increase stats instead.
When he was asked about when he plans to start Part 3 on Discord, which I think may have been around last December or at the start of the year, Ranli said that he is currently aiming for Winter 2025, iirc. Not to be too negative, but, at the current rate of one in-game day every six months, even with the filler weeks, this is a bit too unrealistic, lol.