I too use a multi-pronged strategy:
SHORT TERM BACKUPS / VERSIONING
For all projects that I am currently working on, I save the Dorico file directly to Dropbox. Every time I save, there is a new version available in the Dropbox version history. Because I hit the save hotkey quite often as a force of habit, it is not unusual for me to have a hundred (or more) file versions over a few hours work. In case I delete something that I decide I want to get it back, I only have to find the correct version in the Dropbox history based on the date and time that I saved it. Dropbox does not count these versions towards your storage usage, so you don’t have to worry about this versioning costing money.
Also, when I make revisions, I will frequently save as a new file. In that case, I use things like v1b, v1c, v1d, etc for minor revisions, and go up to a new number (ex. v2) for more major revisions.
On my main desktop PC I have a subscription for Backblaze backup, which backs up all drives on my computer online for a flat rate - in my case, this is several terabytes of data. Backblaze scans for changes every half hour or so, so in general in event of disaster, I will not lose very much. It also backs up the same files backed up by Dropbox, but Dropbox backs things up more frequently (instantly on a save) and the versioning makes it a better choice for Dorico projects I am working on right now.
It took months for Backblaze to complete the initial backup process with my Internet service at home, but once it was done, it only backs up changes. Also, if I need to restore quickly (in event of disaster), I can pay them to ship me a disk drive with the backup contents.
In addition to all this, I take image backups of my main desktop PC with StorageCraft ShadowProtect SPX, which I switched to several years ago from Acronis True Image as I found that Acronis was unable to restore my backups as they were too big - it is a big red flag when you can’t restore from your backup software. A full restore might have worked, but I didn’t want to take that chance. Note: These days, a better and cheaper option is probably Macrium Reflect, but I’m still using ShadowProtect as a result of inertia.
The conventional backups take a full image backup of my boot drive once a week to an external hard drive, with incremental backups happening every hour or so. In event of a boot drive failure, I’m able to get up and running again quite quickly by restoring this image backup. This has already happened to me once, and the ShadowProtect image backup worked brilliantly to get me up and running again very quickly, only took a few hours to restore the 1TB image of my boot SSD to the new disk and I was back to exactly where I had left off. This is another reason I haven’t switched to Macrium - this solution has already proven itself once.
These ShadowProtect image backups to the external hard drive are in turn backed up to Backblaze online, so in the event of some kind of disaster that were to wipe out my home, I could buy a new system and download the image backup from Backblaze online, restore it to new hardware with ShadowProtect, and basically get a clone of my new system up and running as quickly as possible.
I do not use any special backup for my laptop - when I work on anything there, I work directly in Dropbox, so that it is backed up online and synchronizes to my desktop, where it is backed up by the other solutions.