I believe corruption level is factor into whether you get the Empress Ending along with Slut level. If people are not getting their empress ending despite meeting the stated prereq, it's most likely their corruption level is too high from edicts as a lot of powerful edicts increases corruption and each accessory purchase also increases charm and corruption.Your slut level does not need to be that low. I've done runs where I thought for sure I missed the Empress End with a Slut Level of 80-100, but got it anyways (happened again last week, actually). I've also had runs where I was under a SL of 60, but still got the Happy End. It all depends on what passives you unlock, the biggest factors being your Sadist/Masochist levels and first times.
An example would be having barely any negative passives by basically winning every fight through combat, but you attacked so many enemies because of how many days you spent in the prison that your Sadism level was extremely high. I never looked into the code to see exactly how things scale, but people have done the math in this thread multiple times iirc. I kinda just guess based on experience.
A good rule of thumb is just that the longer you stay in the prison, the more odds you have of unlocking a really bad passive that fast tracks you to a Happy End. If you're managing your fatigue well, you should be getting through 2-3 enemies that block progress every day. There's wiggle room depending on your build and approach, but you often don't want to spend much more than a week on any floor. You can stretch this a bit by using sidejobs, but they can make things much worse for you the longer you do them (especially the stripper one).
I just started playing again and got my holy empress title unlocked on NG+ on secretary with a str build.
It's much less of a chore to do on secretary with the additional income and lack of time constraint. You don't need to grind too much if you straddle around low order for subsidy money.
first time around i went to get the pure white stained bride (400+ slut level on completion) on warden. Not hard but a bit grindy since passive gain slows down around 300+ mark.
now i'm trying an unarmed challenge run on prisoner mode with masochism build. Sex build in prisoner mode can hellish at the end but i think you can do it w/ good endurance and energy level even with masochism build.
