Was reading My Debauched Devotion and reminded me of another similar novel that i cant find. I know some reincarnated dude became the sole disciple of some strong female master. Dont remember much except they slept on the same bed with a sheet hanging in between them for some reason. I forget what his cheat was. Edit: I remembered some more: Very similar to https://www.novelupdates.com/series/my-debauched-devotion/ (Start of story)When it was time to chose a mountain/Master he said something to get chosen as her personal disciple somehow. And she has no disciples or has never had a personal disciple. Pretty sure i read it on WebNovel as a trial read a while Back. (Recieved some token from her before or after a disciple tornament) Not sure His Cheat either had something to do with her or he comprehends the Dao instead of cultivate i think.
I'm also quite interested in master-disciple at xianxia- relationships, i'll lurk around and politely come and go every now and then.
https://www.novelupdates.com/series/top-tier-providence-secretly-cultivate-for-a-thousand-years/ https://www.novelupdates.com/series/i-have-refined-qi-for-3000-years/ https://www.novelupdates.com/series/long-live-summons/ https://www.novelupdates.com/series/zhanxian/ There are more obvious ones, and none of those are what you're trying to remember, but these were off the top of my head.
Found it! It was Immortal Hero: I Can See the Success Rate (Only the Beginning was good now that i remember. But it is really short looked and i dropped it like 20 chaps before the end)