Demon Slaying, Gaining 60 Years of Cultivation From the Start

The Jiuzhou Continent contains an era of chaos and fiendish demons, haunted by mysterious beings and fraught with feuding martial families, demonic sacred grounds, and endless struggles between various powers. Conflict is a constant throughout the world.
Within such darkness, Gu Chen opened his eyes to this reality.
At the same time, he discovered that as long as he slew these fiendish demons and ghosts, his cultivation strength could continually elevate.
Killing a Panic Level Demon yields a decade's worth of cultivation.
Slaying a Ghost Level Fiendish Ghost brings thirty years of cultivation.
...
Eventually, one day, staring at the endless swarm of fiendish demons and world-renowned grandmasters in his path, Gu Chen chuckled lightly, "Are you able to withstand this fist of mine, charged with 1600 years of cultivation?"