There is quite a broad range of settings that will give you the exact same rpm on a prop. Some engines even accept 40° advance, while others need only 20°.
Related to the engine needs: early ignition increases the load on the piston, shaft and bearing and detonation may set in.  The engine may be more prone to kick back when starting. The plug will be abused, and the carb is more difficult to adjust right.
A late ignition increases the exhaust gas temperature, but is not detrimal to the engine, and provides sweeter starting with a better adjustable carb.

So find the latest ignition advance point without loosing power, and you will be just fine.