At the beginning we had 2 extractor placed on their respective root.
Everytime we went there they were at 10/10
One day we installed more extractor, 3 extractor on each root, on the same roots, at that moment it started to really slow down. When we went there the extractors only had respectively 1/10, 5/10, 1/10.

So we divided the extractor among more roots and it solved the issue.

If you have 2 extractors per root it will take a bit longer to fill up but it should do the work, but more than that wont be great.