I accidentally messed up the most recent backup, which is why the latest working one is more than a few days old.
Backups require logging into the server and running a few programs to dump about 20-30MB of SQL data and compress it to around 5-6MB before downloading everything (an involved process taking about 2-5 minutes), which is why I didn't backup the site every day. If I were online more often, I could have backed up the site daily, but then I also could have gotten around to automating and assigning the task to someone else.
Right now it doesn't matter though, since the site is no longer hosted on a virtual hosting server with a dozen or so other sites, and I can get to the actual machine if I need to for data recovery. The current server is actually the machine I would store backups on to begin with, so no regular backups are necessary right now.
However, we'll be moving to some different hosting later this year, maybe even as late as early next year, so I'll work out the backup issue then. Being someone who isn't online a lot, I probably shouldn't be doing the backups. When the time comes, I'll put together something and leave it to the site staff members.