Jos 1:1 'And it happened after the death of Moses'
Judg 1:1 'And it happened after the death of Joshua'
2 Sam 1:1 'And it happened after the death of Saul'
2 Kgs 1:1 'And Moab rebelled against Israel, after the death of Ahab'
This division thus seems to represent a single literary conception.
Moses > Joshua > Saul > Ahab
And with the final one, the grammatical pattern of the previous ones is broken.
The breaking of the grammatical pattern parallels the disruption of history spiritually by Ahab.
Scroll division may have been desirable, but not necessary.
An optional scroll break is still different from an indication of literary structure.
Joshua 15,671
Judges 15,635
1-2 Samuel 20,387 + 17,170
1-2 Kings 20,361 + 18,784
So what if you want to divide Genesis?
Genesis 25:11 ‘And it happened after the death of Abraham, God blessed Isaac his son.’
To be clear: this is about physical, not literary, structure of Genesis, which many see as divided into toledoth (genealogies/family histories).
Abraham is arguably superior to Moses (even if Moses is mentioned more).
So we have a sequence of 5:
Abraham > Moses > Joshua > Saul > Ahab
That would spoil the idea of the Pentateuch (5 scrolls).
But if back in scroll days you did need to divide, I speculate that 25:11 would have been a good place to do so.
I'd be interested to know if anyone's speculated that about Genesis 25:11 before.
The observations are more important than the speculation, & one of their main values is to help us remember the text.
RT if appreciated.