How many sputum samples is protocol for aspergillus testing?

Hi,
My understanding from my first pulmonologist and various online forums has been that sputum sample testing is most reliable when done as a set of 3. My current pulmo says 3 is only required when one sputum sample tests positive for NTM. My first sample tested positive for aspergillus (which I have previously been treated for with antifungals). I'm pushing for 2 more but he says that is not necessary with aspergillus. I'm still waiting to hear back from infectious disease doc on whether or not he wants a galactomannan test. As of now, based on CT scan they are both recommending a watch and wait, rather than treating. In general, I'm fine with that approach. I do regular airway clearance, but if 3x sputum testing is the standard, then I want to do that!