It would be good if "natural rest breaks" were not activated if breaks would happen too frequently. 

For example, do not start immediately when locking the machine, if it happens in 5 minutes after the last regular rest break (unless the time between breaks is a similar amount).

By the way, I am not sure enough about this to start a separate issue, but 
sometimes after locking the computer (when of course the "natural rest break" activates itself in the background) the password screen doesn't seem to have the focus when I start typing my password.