Most of us carry or drag a gear pack with us inside a cave, mostly to carry vertical gear, ropes, extra flashlights, food, etc.
If I was descending and ascending a wide open pit, then there is no issue with my rappelling gear or ascending gear, and the pack can go down or up with me. However, when the drop gets narrow and rocky, there may be insufficient room for both the caver and the pack to go together. Plus, if the narrow drop is 150 feet and has already had the rope rigged into place, then we would not want to use the rope itself to drop or lift the pack. We are reluctant to place an accessory rope there just for packs, because then ropes can get intertwined.
The zipline approach works OK in a wide open pit, but not in a narrow squeezy pit.
So, what is the best way to get the pack down and then back up?
Some cavers claim that a small pack can be clipped onto one foot. That would work, but then when ascending, I might need both feet to be independently climbing and chimneying through the narrow sections.