That is a typo in the datasheet. Sorry about that!
The limit should be 133cycles (128+5) in word mode and 261cycles (256+5) in byte mode.
That's because the S26GL064S has a write buffer size of 256bytes/128words.
So you can send the full WB programming commands in one sequence and you don't have to split it up.
Cypress Semiconductor Corp.
Customer Application Engineering