Running on a stand will let you get familiar with your engine before you put it in a plane...The only parts of a gasser that change with use are the piston rings and bearing seals, nothing else in the engine changes much...There is no break in on ball and roller bearings...
Zenoah recommends running the engine in the plane, just a little richer for the first few tanks..
When you can look at the piston rings and the finishing marks are gone they're as good as they will ever get, the engine is broken in....
Maybe the DA engines are set up with closer tolerances between the cylinder and piston...Running rich and not quite so fast lets the high spots on the piston wear away without the engine getting hot and seizing..
I make sure the high needle is set just a little rich and the low as lean as possible for good transition, then fly...