That seems a bit overly complex and error-prone to me. LPs are sent for any blocks found on the network, not just those found by deepbit. Since a lot of the blocks are found by deepbit, your method may work well some of the time.
What you might want to do is log the exact time each share was committed, then add them up for the time intervals extracted from the stats page, obviously correcting for timezone as appropriate. (I'd suggest to both log in and set your deepbit preference to UTC, that way you can be sure you won't need to adjust anything.)
With this method, you may see a tiny amount of mismatched shares around the beginning/end of each round, but the share counts should match more or less.
The announcement in my LP broadcast indicates the pool owner, so i take note, in this case, only for blocks found by Deepbit, also the counter log each share, i make some tests analizing the logs and the result is the same, the counter works well, show the same log info. Yes i could, and i already set the preferences to UTC a few times, when i take some practice there is no diference, i cant identify all blocks...