It depends on your variety of flavoring levels and how important accuracy is to you.
For a tobacco flavor, I make a base that allows for 3% flavoring in PG to be added and still come out at 12 mg/ml. For my ADV, I make a base that allows for 10% flavoring in PG to be added and still come out to the same 12 mg/ml.
And, since I'm not a stickler for accuracy, I'll use my ADV base to experiment with other flavorings since I assume I'll probably use 10% flavoring in PG for most non-tobacco flavors.
For a tobacco flavor, I make a base that allows for 3% flavoring in PG to be added and still come out at 12 mg/ml. For my ADV, I make a base that allows for 10% flavoring in PG to be added and still come out to the same 12 mg/ml.
And, since I'm not a stickler for accuracy, I'll use my ADV base to experiment with other flavorings since I assume I'll probably use 10% flavoring in PG for most non-tobacco flavors.