The present day Schnurle ported two stroke glow engines have a much broader two stroke rpm range relative to four stroking rpm range.

Fifty years ago the baffled piston design engines had a broad 4 cycling range compared with 2 stroking. The preferred tuning point on the ground for these engines was at the top of the four stroke range. When the plane took to the air, the engine would unload into the two stroke range and run perfectly and hopefully not too lean.