If the distributor has a lot of mechanical advance, that method is horrible. Sometimes you get lucky. I've fixed a lot of cars that used the total method.
Using the total timing method to set up a street car is a ROTTEN way to go. It's not even good on a race set up unless the distributor is locked out.
Find the total number your engine wants and run it there. I've had BB's that liked 40+ and others that were 30-32. Big swing in performance running them short of best timing profile.
Simple test. At idle, twist the distributor a little clockwise, if the engine picked up RPM, it wants the timing at idle. Initial timing is finding the point where the engine is running most efficiently where it will still start when hot.
