Yes there is. The amount of hold up time is specified in the flash manufacturer's data sheets.
The problem is that the flash has an internal state machine that performs the charge tunneling as an iterative process: it tunnels some charge, checks the level on the floating gate, and repeats as necessary. If the power to the flash chip goes away or glitches during this internal programming process, the flash write fails in indeterminate and sometimes very unexpected ways.
The problem is that the flash has an internal state machine that performs the charge tunneling as an iterative process: it tunnels some charge, checks the level on the floating gate, and repeats as necessary. If the power to the flash chip goes away or glitches during this internal programming process, the flash write fails in indeterminate and sometimes very unexpected ways.