Su Yuan wasn't suddenly deciding to practice alchemy; he had already considered it the first time he used the Sun Spirit Pill during the Waning Moon Stage.
Previously, it was not a concern; Su Yuan had already progressed fast enough, especially during the Radiant Moon breakthrough, which even surprised himself.
But the Burning Sun Level was different. Cultivation at the Burning Sun level is often calculated in decades!
Su Yuan's cultivation journey thus far took far less than ten years, which shows just how prolonged this process can be.
This was naturally unacceptable for Su Yuan.
Having just the Phoenix Vein and the legendary Soul Card wasn't enough to accelerate; if one wants to further enhance the cultivation speed, then the greatest reliance is on elixirs!
For humans, using spirit plants and fruits directly often leads to wasting a lot of energy.
Moreover, some treasures cannot be used directly, like the Star Core.