Keep it Simple S....
is the guiding principle, use
Calculate Field (Data Management)—ArcGIS Pro | Documentation
the tool goes to arcobjects as does the update cursor
(code can be followed in the following paths
- C:\....install folder ...\Resources\ArcToolBox\toolboxes
- C:\....install folder ...\Resources\ArcToolBox\Scripts
- C:\....install folder ...\Resources\ArcPy\arcpy
A lot of condition checking goes on before the data even goes to a cursor... if you know absolutely that the data meets all the conditions and you will be the only one using the script without providing all the checks... then use a cursor and save you that huge 5 seconds. That 5 seconds would be better spent sipping coffee and not worrying about whether you got everything right.
... sort of retired...