I think mostly because that's what people here saw that worked for some people.Then why are most people needling once a week?
This seems to not make sense because of the healing length.
Is it because of the study's?
If I remember correctly,
The indian study started with once a week for a month, and then continued once every two weeks
The chinese study did once every two weeks.
One study from 2016 did several treatments once every 4 weeks and got results.
So unfortunately we don't know the optimal frequency and what it depends on.
Maybe we will know more in the following months in the thread.