The Legendary Janitor
Most people don't choose reincarnation. Reincarnation finds their way to them. Perhaps they did something great in their life. Or maybe truck-sama wasn't looking where it was going. But without fail, those who reincarnate are destined for something great. A new life where everything changes for the better. But... Reincarnation isn't always the greatest thing. Sometimes you just draw the short end of the stick. Di Tou just happens to have drawn the shortest stick. Pulled out of his life randomly. Taken by a crazy old eccentric man not as a disciple, but as a body double?! And a janitor body double no less?! Grasping a system to find... It's a JANITOR SYSTEM!? Truly, how unlucky can one get?
Researcher
As for techniques in higher stages beyond the Golden Core Realm, it could only be said that the scarcity and quality diminished the further you went.
Cultivation, as the name implied, was a journey of self-growth and evolution, thus, although many cultivators followed similar paths and used the same cultivation methods, in essence each cultivator was unique. This difference was further accentuated the further one cultivated, with the Nascent Soul being a big tipping point. After all, each person's soul was bound to be different, was it not?
For all cultivators, the techniques that best suited them were the techniques they created themselves. Of course, not everyone had the talent to create numerous and high quality techniques, and even less had the ability, or willingness to pen them down for later generations, making considerations for the differences between their own paths and unique points and that of others.