So do I think he opted for abdomen first; however I think he was unsure and wrong.
Just a follow up.
Comparing Nichols to Eddowes, it seems clear from the onsite sketches in Mitre Square that the skin and tissues of Eddowes had been reflected back, as I supposed to allow access to the abdomenial cavity.
That is the tissues were folded back to form what some call a "flap". However this was not removed and left in place.
This to me indicates that there was no need to remove such due to possible to space issues as may have been the case with Chapman. It also differs from Kelly and suggests there was no overall plan to remove this portions of tissue.
Anyone who had cut up at least an animal in the past would know that this method of reflecting skin and tissue was the most efficient way to gain access to the abdomenial cavity and the organs it contained.