I think a big issue is often setting expectations and overpromising things. Also, maybe overreaching. Its cool to have ambition and want to make a great game, and there are several ways to do so. And it is not a negative to want to make a fun game beyond the h-content. But there are many ways to do it.
For this a developer has to ask themselves several questions:
1. What does my audience fundamentally want from me? And in this case this is the CORE audience that you have from early on. Getting in additional audiences is a thing you can build over time, but that appeal needs to be secondary in priority.
2. What would I like my game to look like and play like in the end?
3. How much money do I have (per month/quarter/half/year) to invest in this project?
4. How much time can I (and everyone on my team) invest in this project (per day/week/month)?
5. What amount of content seems appropriate (monthly/bi-monthly/quarterly) with each bigger update?
6. Where does my storyline start (, where - roughly - is the middle), and where is the end ? How many endings will there be?
6b. What are the main paths I want for my character. Pic..... 3 or 4, each with a different theme/fetish, each potentially having one specific character or maybe two, that it is tied to (among the cast of side characters).
7. What are the main fundamental gameplay mechanics I want in there? (i.e.: turn-based or real time combat? platforming? searching and puzzles? reaction time based events? decision paths? upkeep mechanics like hunger or corruption or lust/momentary arousal, etc, etc)
8. What could interesting events be that I can tie to the above mentioned paths/themes and fetishes and which one of those would be one-time events and which one could be repeatable? What are the conditions for the repeat in order to not have the player go through the same event multiple times in a row, but rather experience the same event at different times, more stretched out, and rotating with other events, so it does not feel too repetitive? And how does that make sense in terms of story and natural progression of the character's mindset and the point in the story that they are at?
Now, these questions build on each other. I might not have listed all important ones, and I might have listed some higher that others would have put lower. But generally they follow an order. Because the ones above are the most fundamental questions, and the further you go in the more specific it gets.
In the end, you need to set the audiences general wishes as the top priority, after that come your own wishes and vision. Those need to agree with the financial budget and the time budget you have, and they need to conclude in a concrete plan of action that has to be roughly followed. As time goes on expectations will be adjusted slightly with experience, since some stuff will take more time than expected while other stuff will take less. Still, setting those expectations early is important.
And that is one key point. Im not going to hark on it too long, but going in with a vision for a game, having decent progress till version 0.8, then having irl issues stopping production, then relaunching is one thing. Then add on top a utopic vision for the games new scope and quality which clashes with the reality of what you end up producing, for you having to backpedal and adjust the vision down in scope again, but having to start fresh again because of that. But having a decently sized team (some succesful Indie Games need 2-3 years to develop and are done by one dev goddammit), some of them supposed professionals from the broader non-h industry. Telling people you will work on it hard and honestly. Then having a slow dripfeed again projecting the project as finished in 10 years roughly, if it keeps going at that pace.
Now Im not in their discord or other forums, so its possible I lack details here. But from my POV, there is no clear sign if these people are all working part-time, full-time, are getting payed or just do it on a "free time" comission basis, etc, etc. So assuming what was said before is true and some are working at other things, this does two things. First, it reduces production cost, which is great for them. But second, it slows production time, which in their situation is bad. In a case like this, it needs to be extensively communicated through all possible platforms that this is going to be a very slow process and that the "dev team" are all having other full-time jobs that gets them money on the table but that also prevents them from doing "normal" full-time level amounts of work on the game. Hence the slower pace and the bottleneck in the pipeline.
Again, these ecpectations need to be set, and they are often not. Im not only talking about this project here of course.