I found a freeware application that seems to do the exact thing I want, which is to reduce the frequency of Time Machine backups from one hour to something less frequent. It's called TimeMachineEditor. Apparently this application does nothing more than edit the plist for Time Machine, which at least sounds safe. Another alternative, TimeMachineScheduler, substitutes its own daemon, which sounds less safe. Does anyone have any experience with TimeMachineEditor. Can anyone think of any downside to using it? Thanks!