had been authorized to have a multiple day layover (I was on leave) in Texas while enroute to Italy since it was an OCONUS PCS. If I had been PCS'ng CONUS, I would not have been authorized a multiple day layover (even if I had been on leave) in Texas
It seems to me that you mean the Government paid for your ticket to Texas, you stayed there for a few days, and then proceeded to your OCONUS location.
This was likely possible due to how your initial flights were set up by CTO/SATO. (AZ -> TX -> Italy) If the flight ALREADY sends you to TX (through the natural booking of the ticket/use of International airports etc) then you should be able to spend a few days there and continue the journey.
However, if your flight doesnt go through the stop you already want then they will not change the ticket for you (esp at a cost loss to the government). For example if your flight to Hawaii is: Italy -> RFK, Wash DC -> LAX, Cali -> Hawaii... then the Gov wont change it to get you a stop in the middle to go to TX. This would likely shoot the cost beyond acceptable (this para mostly sums up Auto's point).
But then again what do I know, I could be totally wrong about the whole situation?