not sure if this idea has been brought up before, but oh well
the ability to make policies permanent (in some cases probably in a somewhat nerfed state) if you have done them often enough. lore wise i guess you have lived multiple weeks like that so you start to act like that subconciously. if you choose to make one permanent, it obviously gets removed from the rng pool the weekly choice draws from. maybe the option to un-perma at said weekly choice, tho if it should be re-added to the pool or just sit on a list waiting to be "re-perma-ed" is a good question
doing this could obviously influence dialog/scenes where applicable. what does it mean if reading week becomes permanent? or bento week? or training week? or imouto week(wholesome cuddles or even just sharing a bed no lewd attached)?
or the one that started the idea quite and is probably the only one that could turn this feature from a neat QoL lategame gimmick into "welp, this shakes things up endgame", complete openess. im not talking about just "flash dick gives (nerfed) +1 trust/interest forever and never fails". im talking about taking the whole thing a step further. things like peeking no longer existing, because you can just walk in no problem. effectively completely removing shame and sense of personal space from both directions, maybe while adding a few scenes that give the sister more "agency". i woldnt be surprised if half the dialog and scenes with the sister should be influenced by this(heck, that should already be the case if you really think about it, it just isnt. "complete openess" week but gets kicked out if walking into the bath even if she didnt do any lewd). yes, there should prooobably be very high trust/interest levels needed for this, maybe in stages. it would also gove those super high numbers a purpose(1000 or 2000 is effectively the same rn afaik, please correct me if i am wrong)
heck, i am semi tempted to learn how to work on this game just to make the base mechanic of permanent policies if there is enough demand and no one else wants to. once the base mechanic stands, most weeks should be just some very few and quick dialog changes at worst