Having multiple backups are a must.
- TimeMachine is mostly when a macOS update fails. I hate the interface for restoring files. On High Sierra there is no notification when TimeMachine isn't done. I'm not using TimeMachine on the newer computer. So this needs to be checked.
- Carbon Copy Cloner (yes, it's still working fine) to an external hard disk. I send myself an email every night so that I can check that the backup was done.
- Acronis for when the house burns down. Online backups all suck lemons. Yes, I've tried multiple and they all suck. I get hourly emails for completed backups.
- Version control for software development and Rapidweaver.
- Extra backup of important data before doing a macOS update.
- My own app Mail Archiver for the emails because on newer versions of macOS TimeMachine doesn't restore emails.
- YummyFTP to back up my websites.
Yes, I'm paranoid about my data. And yes, all backups have had failures when I needed them. Therefore, the emails when a backup has run.
Edit:
Arq is the worst software I have ever used. Totally unreliable.
Using iCloud as backup is dangerous. It can fail without warning or eat your files.