Narkissos
No, each of the three step model is well supported by biblical and secular evidence. Now that does not mean for example 539 that WT scholars used all of the secular evidence which may well contribute to the use of competing dates. But such scholars looked at the evidence and assessed that 539 was solidly based upon secular evidence, universal acceptance within scholarship and was well described as momntous biblical event well grounded in secular history. This 539 is truly a safe and secure foundation for establishing a relative chronology. But if you prefer other candidates then that is fine because chronologists generally select their own methodology but if it does not work do not come complaining to me.
Chronology is about methodology and interpretation and that is the Golden Rule. It does not matter whether it is the chronology of Narkissos, Jonsson, Ussher, Thiele or WT the abbove rule applies. The seventy years interpretation whatever the case. I will let you into a tweeny-weeney secret- the land was desolated for seventy years without an inhabitant in order to fulfill Jeremiah's word. It seems that you prefer the modern critics opinions over and above what God's Word clearly states.
scholar JW