[swamp40]

You can't typically write just 1 byte into flash - you have to write in pages of say 4KB.

And writing to flash is painfully slow.

So it's most efficient (current-wise) to store up 4KB worth of data in RAM and then write it all to flash in one fell swoop.

It's a tradeoff with data security, but I think it's a good tradeoff because only rarely will things go wrong, but the additional current burn is guaranteed and constant if you write every datapoint to flash.

Magnetic FRAM is making a comeback just to scratch some of these low-power itches. It's faster, uses less power, and has greater write endurance. TI even put it in one of their latest MSP430's.