It is also useful to note the following as well:

* The QUANTITY or QUALITY of your materials gathered during your successes does NOT matter towards reaching fatigue.

In Example:
PLAYER A goes out and fished for 150 sucessful catches before reaching fatigue. Each and every one of the catches got them only 1 fish at a time at normal quality. (Call this the Minimum possible)

PLAYER B goes out and fished for 150 sucessful catches before reaching fatigue. Each and every one of the catches got them 3x <fish name> at +3 quality. (Call this the Maximun possible)

As you can see, there is a range from the above example of 150 - 450 actual resources, but the fatigue level is the same. Therefore when gathering with the intention of maximizing your resources for your allowed CAPPED POOL of sucesses, one should not only focus on gear that improves Perception (increases Quality of resources) but have abilities equiped that also improve the quality as well.

As far as catching/harvesting multiple items from a single attempt, I'm really not sure what affects this (Stats, gear stats, rank, etc...likely a combo of all of it).