Gas Clouds

How are people able to farm Gas Clouds so extremely efficient?
When I tried to figure out what the respawn time was of the clouds (becuase I could never find 1) I noticed an army of players come swarming at clouds just mere secconds before it respawns. How do they know where and when to be there?
This makes gathering clouds for the normal player undoable..

they have a 5 or 10 minute repawn, cant rememebr which and they always spawn on specific locations, not all of the retail ones spawn

All of retail ones spawn in exact same locations.
The guy who took 1 cloud 2 times in a row knows spawn time.
It just requires practice and some personal skill.