[MichaelBick]

For some reason I remember them being max 15 minutes long(I could be wrong though so please correct me if I am). You only have to back up new information, so I can't fathom it being that long. Very few people are on from 1-4AM anyways(except for the people in Israel), so I think most people prefer the quick backup every day that almost always doesn't affect them over a much longer backup every month that would likely bring the sight down for a significant amount of time. The daily 15 min backups would turn into a 7.5 hr backup.