Yes & No. On a PC go to Window > Preferences > Files.

The Models directory refers to the location where your autosave files will be stored.

But, the only autosave files that are saved to the default directory are ones which haven't been saved. i.e. open a new file 'Untitled' work for a bit, then SKP crashes, the Autosave_Untitled.skp file will be saved to the specified directory.

In all other cases the Autosave file is saved in the same folder as the folder that the SKP file is in. i.e. open Project_X.skp from Project X folder, work on it for a bit, then SKP crashes, the Autosave_Project_X.skp file will be saved to the Project X folder.

SketchUp also saves SketchUp Backup files. those are the .skb files that show up in the Project X folder. I know alot of people find them pesky 

-mike