Cycle base or tannin based.
I try not to change water until the cycle is completed on a new tank.
Tannins getting the water too dark is the trigger after that for the first year.
Could be once a week or month, it's a looking at it thing.
Beyond changing for tannins it's like any other tank and population level plays into it.
My dirt tank water changes are partial (20-50%) once a month out to once every six months at the longest stretch I've logged.
Sorry to be vague but it varies.