That's what is meant when you hear about "tuning" your combination. It is becoming a lost art.All you can do is test, every combination is different, as is every different brand and grade of fuel. Cylinder head chamber shape has a lot to do with it also.
That's why nobody will just be able to say "yeah, jack it up to 40° and it'll go like stink" and guarantee it will be the ideal point.
You've also got to test timing and jetting together....just adding more timing it might slow down, but adding more jet and more timing it might go faster yet