Some of the systems I worked with couldn't do a full backup during a day for the massive data changes. An incremental backup ran each hour, and then over the weekend we could run a full. But yeah, backups take time, especially in those days using tape!
The worst thing is when you've done an update and realize you screwed up and made something worse. One time I updated the data in a whole table, set one of the columns to the same value... throughout the whole table. That was nasty, especially considering that the data was generated through a slow process that had to take a lot of other data in consideration. It took me a week to re-run the generator. Bleh.
