Oil Consumption

I now have 3500 miles on my engine rebuild, 3000 since the last oil change and the motor does not burn (or leak) a measurable amount of oil. I guess that I would consider this another plus for the engine rebuilder along with the super performance of the motor so far. Was this engine designed to burn a significant amount of oil? Why would you get such divergent oil consumption numbers (within factory stated “tolerance”) for Porsche engines as they rolled off the line new?

Joe
'80 SC Targa