While it’s true that “It depends on your business needs”, most often I’ve seen backup schemes which work on a minimum of a daily backup of most data. For example, on a larger, busier system, it might have a full backup done over the weekend when the system isn’t as busy and therefore has a lower business impact. Then daily differential backups are done each night. For smaller systems, it might just be a full backup of critical data every night.
For highly active, critical SQL databases, I’ve also seen this extended where the a full backup was done of the database weekly, with differential backups done nightly and transaction log backups done every 15 minutes. This obviously had full transactional logging turned on for the critical databases.
As a concrete example, on my home “server” (desktop with delusions of grandeur), the main data partition is running on ZFS with snapshots taken every 15 minutes, hourly, daily, weekly and monthly. The 15 min. snapshots are kept for an hour. Hourly snapshots are kept for 24 hours. Daily snapshots are kept for 31 days. Weekly snapshots are kept for 8 weeks. Monthly snapshots are kept for 12 months. There’s a bit of overlap in the daily and weekly schedules, as those are most likely to cover my arse from an “oops” factor.
The downside of the snapshot setup is that it doesn’t provide disaster recovery. And, I’ll admit, for my home stuff I haven’t gotten around to sorting this out. Ideally, I should be taking a weekly backup, compressing and encrypting it and pushing it to a cloud service somewhere. Laziness has meant that hasn’t been done yet.