Thanks.
I can assure that I have spent hours reading the posts in this forum, but still had doubts.

My main question is, why some people (like you) prefer 35-45% duty cycle if (due to close loop control) every setting (between the 0 and 100% limits, of course), will lead to the same mixture?
Is that because under load conditions you must have margin to enrich the mixture even more?
In my case at 2000-3000 rpm the reading is around 25%, that seems the reaction to a lean basic (open loop) setting. Am I right?

I wonder what happens when my engine is at full load... is there enough margin for the ECU to enrich the mixture?

Thanks again.