Power Fc fueling method

What is the proper method for fueling changes. I've heard 2 theories. Tuning fuel with the Inj Map, and tuning fuel with Base map. Some people say to set the Inj map as a target lambda, and tune the Base map to hit the Inj map values. Others have said to set Inj Map to 1.0 and just tune the Base Map. Which do you guys prefer and the advantages and disadvantages if done one way or the other.