I’ve noticed that whenever I close Scrivener for Windows, I get a little window that says “creating a backup”, with a little progress bar that takes maybe 10 seconds to complete. I’m not familiar with this behaviour from Scrivener for Mac. I just wanted to make sure that this is intentional and that I haven’t somehow triggered a setting that is creating needless duplicate backups.
If you haven’t changed your settings, then you won’t be generating numerous backups beyond what is reasonable. The default limit is set to keep only the five most recent states your project was in when it was last backed up. For most people that will be around a week or two or work.
You can read more about backups in the user manual, in §5.2, Backing Up Your Work.
Mac Scrivener behaves in the same way, always has.
The default settings generate a backup whenever you close the project. Whether you see/notice the “backing up” window depends on how long the backup takes: project size, system speed, etc.