MacUpdate can be configured to scan the source directory at a specific time each day by checking the “Daily Synchronization Time” checkbox, and filling in an appropriate time. Of course, for this option to work, MacUpdate MUST be running at the desired time. Another option, to scan for updates after a specified amount of time has elapsed, is implemented by the “Synchronize Every X Hours” checkbox. If this box is checked, MacUpdate will scan the source and destination for updates every X hours, where X is the value entered into the text box next to the checkbox.
MacUpdate is well-behaved in the background, and only takes 300K of your precious RAM, so it is possible to just let MacUpdate run all of the time. Throw an alias of it into your Startup Items folder to have MacUpdate immediately launch on startup. If you like, check the “Synchronize on Startup” checkbox to immediately scan for updates when the Mac is powered-up regardless of what time it is.