I have auto-save checked with "Number of versions to keep:" set to 4. (Auto-save set to every 15 minutes or 70 changes)
It is only saving 1 version.  
 
The main issue is this version got corrupt when SONAR locked up.  I had to force close the program with task manager and now lost several hours of work.  My settings and the folder showing only 1 backup.
 

Everything looks OK. Auto save only makes one copy called starting with "Auto-save"; the files ending with a time stamp are the 4 versions made by the version setting.

Only comment  I have, is that I have never seen all those other files in my folders? I have just the Audio folder, the CWP file and if there are back ups those as well. The back ups are still CWP icons with Auto Back up copy added like you show there for the one. So what the heck are all those other files are those the versions? Anyone?  I've never used versions. 
Also I see the back up is much smaller than the original. Notice you saved the original manually at 1:59 but your back up didn't happen until 4:15. That's hardly 15 minutes so something is not working. I don't use Auto save much as I don't trust it. I only activate it when with a client and I don't have much time to spare to make back ups. 

The files with the .asset extension are created for Gobbler. There is a Preference setting to skip creating them. The ones ending with time stamps are versions which have nothing to do with auto save.

Thanks for the info.  It would be handy to have more than 1 auto-save.  All the other files were from another day so they did not help me.  
1. Do you know what triggers when the files ending with the time stamps are created? 
2.  Are the .asset files of any other use than gobbler?  Since I don't use gobbler, I will probably disable the creation of these files.  It looks like the setting "Save Asset Manifests with Project" may be the setting for this.

Manual saves
No, only Gobbler. That is the preference setting.

martinv
1. Do you know what triggers when the files ending with the time stamps are created? 

One thing that does is if you have file versioning switched on. There's a setting for it somewhere in preferences. What it does is every time you save it creates a fresh saved copy and rather than deleting the older save file adds a time stamp to it so you can tell it apart from the most recent save. You set how many older versions of the file are kept in preferences. In your case it would appear to be four.

Versioning is very useful because it means you can get back to where you were in the past if necessary simply by loading the relevant old version of the project. It's got me out of a mess several times when I'd changed things in the project, hit save, then decided my latest changes weren't such a good idea after all. It can also be useful if you get the dreaded "corrupt project" problem.