I found this on another site and believe it to be credible and make sense:
 
 
Rings rotate in the grooves unless they are pegged .
The spring of the ring does not create the compression, it is the gasses trying to get past the ring which forces them out to make the seal with the oil on the bore & in the ring groove .
This is why on 4 strokes champhers always point up.
When new the rings have not made their seal against the bore so spacing them 120 degrees helps the initial compression.
 
Of course a shop manual would give you conclusive answers...
 
 
 
.
 

There's an oil hole in that recess that CANNOT be covered up,
IE; seal NOT PUSHED DOWN FULLY INTO THE HOLE..
 
Anywhere in the cover leaving the oil opening clear AND the working part of the seal fully intact with the crankshaft. 
A little oil between the crank and seal wouldn't hurt Flush is fine and you should still be able to see the opening... 
 
*As a side note, on my 18HP Briggs, that seal started leaking after 5 years. 
I took a short cut and pulled it with the engine in the machine
(drill and use sheet metal screw to pull the seal-
Ultimately nicking the crankshaft.) 
Now THAT FIX- Pulled the engine and cover
and seal.  I had about 1/4 crankshaft NOT damaged on the end not damaged.
I put the seal into the case, JUST ENOUGH to catch the case and ride on the 
un-damaged part of the crank.  Used Yamaha case sealer on the outer edge of the seal.
There was just enough "good crank" and just "enough cover" -
Re-assembled, stayed and is currently nice and dry..
(A major screw up with a positive ending)
 
 
.
.

Also, I started the engine with the mower blades engaged and ran it for 20 min at medium rpms. I didn't realize the blades were spinning. I didn't drive or mow. Would you expect that to effect the rings breaking in? Or anything else?
 
thanks