Hi Jennifer,
A lot of this depends on your customer base, but I know for my organization, having the score reset every day and then re-score would not work. Our buying cycle is generally 6 to 12 months, so scores don't aggregate swiftly enough to be re-scored every day. We do still include a score degradating element to our process, but we do so as separate campaigns - basically a "if no activity in X amount of days, reduce by X amount."
From what you're describing, if you wanted to retain score information for activity in the past, you would have to run two batch campaigns every day: one to remove all scores and one to add amounts based on those previous activities. The second campaign would have a lot of conditional work flows. It would have to be extremely specific. For instance, we give +2 when someone opens an email. If I were to erase all scores every night, I would have to then create a batch campaign that would look like this:
Smart List: Opened Email, Email IS ANY in past X days.
Flow: I. Choice 1: If Opened Email, Email is Email 1, Change Score +2, Default: Do Nothing
II. Choice 1: If Opened Email, Email is Email 2, Change Score +2, Default: Do Nothing.
OR I would have to create separate batch campaigns for each email that I sent in a certain amount of time. And that would not include the webinars, website downloads, video views, etc.
Instead, we leave the score alone save for the trigger campaigns that add an amount
each time the individual does a certain action. To cap the amount, just add the condition that if "score >= 100" do nothing. Then, as we do, you can run a separate campaign to degrade scores over time.
The key is that while demographics can easily be rescored as batches, behavior is trigger-based, and trigger campaigns don't work on past activities, so you would have to complex or multiple batch campaigns in order to accurately score.I would be interested to see if another group has scored this way, especially in a faster-paced buying cycle that may need be refreshed more often.
UPDATE: I forgot about this resource, but when I was revising our Lead Scoring campaign, I found this guide super helpful. You can download it here:
http://www.marketo.com/definitive-guides/lead-scoring/.