I think that the Data > Thumbnails > Create and Data > Thumbnails > Update functions should be merged into a single function.

Simply put:
If a file doesn’t presently have a thumbnail, create it, move to next file.
If a file does have a thumbnail, update it, move to next file.

I use these two functions so much that I have assigned them keyboard shortcuts in the Mac OS X System Preferences. But it’d be really great if they were one function, not two.

Actually that’s what Thumbnails > Create does whereas Thumbnails > Update updates only existing thumbnails.

You know what, nevermind. I dunno what I was thinking. It makes sense the way they are now.