BIOS flashing question

i have an older k7s5a ver. 3.1 that had a 1 gig thunderbird 266.
i am moving up to the xp1800 thoroughbred.
i went to the ecs webpage and looked at the bios versions newer than
my original 11/09/2001.
i saw the one dated 02/02/06 that was for allowing it to run the new
amd cpu.
i downloaded that and flashed my bios. it worked fine from what i can
tell i haven't gotten the new cpu yet.
i have since seen information that the newer bios dates always include
the features and updates in the prior bioses.
if this is true, why does ecs offer all the versions of the releases?
why wouldn't they just have the newest version of the bios for each
motherboard model?
would the latest version update my board for everything the previous
versions did? i am wondering if i should just leave it alone now that
i have updated to run the cpu i am getting, and any hardware i have
now. or if it would benefit me at all to use the latest bios.
i will not upgrade this board again because it won't support above 266
and i am sure my next upgrade would be at least that.