Can't find enough Corrupted Nexus

I'm level 91 and only unlocked 14/40 atlas points and all I do is go from tower to tower to try and look for corruption. Right now there is 0 sign of corruption, even in the fog where you can look at the head of the towers to see hints of corruption, there is nothing.
I haven't done any juiced maps yet, just running around exploring trying to get my points. Is it really supposed to take 100s of hours to get all the points?