Keeping their movements a secret had fallen apart. Shy had begun to actively stomp on the threads left behind by other glacial spiders. The sudden bursts of ice were nothing to the glacial spider body she was controlling. It was also assisting in her learning when it came to how to move such a larger creator.
Since Shy was smaller than the Glacia spider by a significant amount, she had a large learning curve to chase. The threads that she could create were numerous. This had been seen when she had attacked during the tournament. At the time she had only been able to create them for a moment. With so much shadow energy from the shadow crystals, Shy could create them for longer.
However, right now she was using far fewer to manipulate the insides of an already dead beast. It was a decent quality since the group had not dismembered the glacial spider. That alone gave the glacial spider more energy left within its body for Shy to use. Therefore, it slowed the degradation.