Cause fight lasting is based on item. This one is 12000 seconds.
Anyone can add a count towards a cause, and when there is enough count, the person with the needle uses it to activate the effect.
You can view how many causes in the trigger box with their names.
"for example, we have a fight cause named [i]killeno[/i], with 10 counts. needle A was used, will it consume the 10 counts and reset the counter to zero? i am thinking what if needle B, needle C, so on and so forth, are to use the same fight cause following needle A"
The fight causes stay after you use a needle, and hasn't been tested if you can use more than one needle for the same cause yet. Could try to find out.
"and is it possible we gather/farm fight cause counts for days/weeks then use the tool until the people fighting for that cause are satisfied with the counts (assuming counters are permanent until consumed with the use of the needle)?"
Counters only lasts around 10-20 minutes, not fully sure how long, and only a limited amount of uses with the needle (which I assume can be re-picked back up once fully consumed)
Sorry if that's not what you're asking, was kind of unsure.