Just a slight correction: It's every 2 hours for Kaspersky instead of 1.
To Aggravatorx, Kaspersky checks for offline database updates every 2 hours and KSN syncs online every few minutes to protect against new malwares for which it doesn't have any signatures yet. Thanks to KSN, Kaspersky is always one of the first to response to new threats. Kaspersky's static scans also checks hashes against KSN database for unknown files, hardly any other AV does that so don't be bothered about KSN syncing all the time as it does that for protection.