The system's current implementation relies more heavily on feeds than the original design. Frequent publishing of feeds will increase the stability and integrity of the system.
However, AFAIK currently delegates must pay a transaction fee to publish a feed. I think a delegate who has published fewer than, say, 200 feed updates in the past 72 hours should be able to publish a feed update for free (no tx fee).
The quota should be high enough to allow delegates to allow rapid response in volatile market conditions, but low enough that all delegates regularly filling their quotas would still use only a negligible amount of blockchain storage.
Scripts should still defer publishing updates due to tiny price movements, to conserve quota which can be "bursted" if a volatile condition occurs later.