Even the heavily modified version of the Body Refining Potion was developed for Spirit Controllers at A-level or higher. Under normal circumstances, Spirit Controllers below B-level had no bottlenecks when leveling up. Even if they did, the issue would be with their spiritual power, not their physique. Only at A-level and above could a lack of physical strength prevent one's Spiritual Power Level from advancing!
For her first attempt, Ning Xuan only added three vials of the Body Refining Potion. She knew that because she cultivated the Guiding Spirit Scripture, her current physical strength far exceeded her Spiritual Power Level, so she added a little more than the standard dose.
