Scrivener has two manual backup commands you can use, even if you leave the project open for extended periods.
The first is File > Back Up > Back Up Now and prompts Scrivener to create an immediate backup of your project in your default backup location.
If you’re in the habit of leaving your project open on your computer, I recommend using that command either just before you make a lot of changes to your project or right after doing so. Or, if you increase the number of backups you’re saving, you could do both.
The File > Back Up > Back Up To… command will allow you to direct where that backup is saved. This can be a handy way to make a second backup copy on a USB drive, a cloud-storage account, and so on. It also allows a user to either ZIP that backup or leave it uncompressed as needed.
I also recommend reviewing @kewms’s post Got a backup? for best practices on protecting all your most critical data. Including your Scrivener projects.