I find the the behavior of File --> Save As to be a problem for my workflow. By default, Photoshop checks the "As a Copy" option when you choose this menu item. If you accept this default behavior that means it creates a new copy of the file with the specified name BUT this new file doesn't become connected with the file you still have open. That document retains the original filename. This is different from every other Windows program including other Creative Suite applications.
This behavior repeatedly trips me up because I think I'm saving the current document under a new filename--but this is only partly true. When I go on to make further changes and then do a subsequent save it's overwriting my original file--which is not what I'm expecting. So, I end up modifying the wrong file.
I'm getting used to this behavior but if I forget to unselect the "As a Copy" option Photoshop messes me up. You have to remember to deselect As a Copy each and every time you do File Save As for a new file. It defaults to this behavior with each new file even after deselecting the option one or more times during a session.
Personally, I would prefer to have Photoshop behave like all other Windows apps and immediately connect the new copy with the open document. And, for that matter, I'd prefer not to have Photoshop append the text " copy" to the filename. That's almost never the text I want so I'm constantly deselecting that, too, and replacing it with my own text.
At the very least, it would be nice to have an option in Preferences to change this behavior.