It depends on the server and what it holds, but most servers get a daily backup to S3 and a weekly (live) snapshot of the full system. Some need hourly backups or real-time replication, while others don't even really need weekly backups. Haven't ever needed any of them, but it's reassuring.
robzilla
6:51 pm on Mar 31, 2017 (gmt 0)
Should have knocked on wood. Needed a backup today.
not2easy
8:47 pm on Mar 31, 2017 (gmt 0)
CarbonCopyCloner (OSX) has a sale today in honor of the occasion. (disclosure) No affiliation with them but I do use the product.
keyplyr
10:16 am on May 3, 2017 (gmt 0)
Currently using managed hosting so nowadays I just make a copy of my local files that include my 3 sites to an external drive. I do this each Sunday and keep 3 weeks legacy. It's really all I need.
I've needed to retrieve files, usually htaccess, several times over the last couple years.