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?
In any case, although Di Tou's Spiritual Sense could in theory stretch out very far without issue, for practical reasons, Di Tou never stretched it out that far, and his 'safe' range was within a kilometer or two, as in this range he could both quickly respond, and have a durability to his Spiritual Sense that allowed it to resist most cultivators below the Nascent Soul Stage with ease.