When you have multiple computers, you might want to put your files on a USB flash disk (aka a thumb drive or jump drive), and backup data to your computer's disks.
Create a folder called "backups", and a folder within it called "usb", and copy your files into there. If you have automatic sync software, you can set it to backup the data frequently. Hard disks are so fast you won't even notice the backups.
Set this up on all your computers, and your risk of data loss is nearly zero.
Just let the data "settle down" and force a file copy before removing the USB flash memory.
You could also set up a similar scheme with a USB external disk. The only issue is that moving hard disks tends to damage them and lead to data loss.
If you have important data, consider using encryption software. Losing the USB flash drive with your vital data would be bad.