Requirements to change condenser fans for refrigerant retrofit

I have a no-brainier question.
Under what conditions could it require to replace condenser fans with better air flow when retrofitting R-22 system with alternate refrigerant :confused::confused::confused::confused::confused:

From my experience, condenser fans are normally designed to suit the maximum heat rejection of the condenser, by the manufacturer.
If you are considering changing refrigerant to one that has less capacity than the original then I would advise changing the head pressure control to suit if the existing isn't able to compensate -no need to change fan
If your refrigerant change is to one with more capacity then your condenser will be undersized.