Comment 14 for bug 479191

I don't see how network zones can have any effect on scheduling, since the network and scheduling are completely unrelated.

My use case involves not tying up limited netbook resources at times when I know I'll need full access to my machine--such as when I'm teaching.

The current scheduling options look like this:

How often to back up |_________v|
        Keep backups |_________v|

It wouldn't complicate things too much to add a "Manually specified" option to the frequency combobox. When "manual" is chosen, the following interface could appear (_*_ indicates a text box, |_*_|v| indicates a dropdown box, and [ ] indicates a checkbox):

Backup every _1_ |_Days_|v| # Other options: Minutes, Hours, Weeks
[ ] At [timebox] # Grayed out if the interval doesn't make
                             # sense for this option to be available.
                             # Optionally, there could be a button
                             # to add additional timeboxes, but one
                             # should be sufficient for most cases.

I think this interface would address most use cases and wouldn't add significant complexity to the interface.