Thanks Jellby for your explanations. You know me indeed, I never stopped wondering...
I had used a while the "alternate" setting but I found it more confusing than helpful. It so often started with the wrong one...
Maybe the KSM07 menu name regarding both "handle update" could be changed in a more explicit way: The meaning of "handle update" and "handle partial update" look very close but may cause mishaps for some uncautious users like me.