>>(2) Not sure if the original reason for limiting time frames was to limit server load or to improve response time for for the user doing the search...[snip]
>
>AFAI remember, both reasons. Fixed time frames allows for storing each 6 months in a separate table, thus performance improvement.

Fair enough, though I'm sure you can imagine some workarounds that would buy the best of both world's...fixed search set size with floating bounds updated on a daily (or weekly?) basis.

What about my first idea of 'search back in six month increments 'til you find at least one or fail altogether' ?