When an AC / refrigeration technician sets the "superheat" (fine tunes) an AC or refrigeration system, he is essentially fine-tuning it for that instantaneous external and internal heat loads at that exact unique moment.
Internal and / or external heat loads change quickly, so the system very quickly can become ~15% less efficient.
THIS IS COMMON TO ALL AC AND REFRIGERATION SYSTEMS.
“After setting the superheat manually, the internal and external heat loads naturally change fairly quickly, and the system becomes ~15% +/- less efficient.
Costing 15% more to run and producing 15% less cooling