Both the original approach as well as the proposed one are wrong. The correct approach for marking multiple packages for installation is to
1. mark all the packages with auto_inst=False, auto_fix=False
2. mark all the packages with auto_inst=True, auto_fix=False
3. run a ProblemResolver manually
This ensures that choices are propagated correctly, if you install A, B and A depends on C|B, this would install A and B, whereas the other algorithms install A, C, and B.
Both the original approach as well as the proposed one are wrong. The correct approach for marking multiple packages for installation is to
1. mark all the packages with auto_inst=False, auto_fix=False
2. mark all the packages with auto_inst=True, auto_fix=False
3. run a ProblemResolver manually
This ensures that choices are propagated correctly, if you install A, B and A depends on C|B, this would install A and B, whereas the other algorithms install A, C, and B.