Do you want more purges on a server you run, or in your singleplayer / co-op game? Then change this:
“Purge Meter Update Frequency” in the admin console
also known as
ClanScoreUpateFrequency in the config file
And make the number LOWER. The default is 15, so setting it to 5 makes the purge meter fill 3x as fast:
“Purge Meter Update Frequency” = 5
also known as
ClanScoreUpateFrequency=5
The tooltip in the game (Settings - Server - Purge) for “Purge Meter Update Frequency” is WRONG. It says “Raising this will make the purge value increase faster”. After hours of testing on my own server I can confirm the meter fills FASTER when the number is LOWER.
One easy way is to check and see how long it takes to see the purge meter show up after you login. Those numbers are roughly minutes. The default of 15 means it takes about 15 minutes for the purge meter value to update. When you lower it then it shows up much faster. Try a “1” as an experiment. 
Want to see a value of 5 in action on a public server?
(RP-PvP) Fleetwood - Bldg Dmg Off, x2 Purge, 4am EST Reboot
108.61.124.68:24000
40 people / no password
https://www.battlemetrics.com/servers/conanexiles/2269865