Automatically generate thumbnails for all subfolders of a directory in Windows 7?

Is there some way to get explorer to generate thumbnails without actually having to navigate and scroll through every folder?

All I could get was a command prompt script that would load an explorer window for all subfolders, however only images that were visible would have thumbnails created.

I made a free open source tool for that purpose: WinThumbsPreloader.

It requires Windows 7/8/10 and .Net Framework 4.5 (included in the installer).

Just right click on the folder to call the context menu and select WinThumbsPreloader > Preload thumbnails recursively in the menu.

Go to the top level folder and in the search box (top right), search for *.jpg or whatever your image file type is. Change the view to "thumbnails" and shrink it down as small as it'll go. You may need to page down a few times to get them all to generate.

That's the only method I'm aware of.