Mind you (you probably already know about it, but perhaps for others newer to PM), you can use the lightning bolt icon in Save As... dialog to save your current Save As preset (including size and folder destination), and file destination fields in the dialog allow variables.
So you could set a destination to for example C:\Export\ + {folder}_size3000 (if I remember the folder variable correctly), set size to 3000, and save the whole bunch as one preset via the lightning bolt, and create a second one with size2000, and third with size960, If you get my example. Or if you could use another variable.
You would still have to invoke the save as three times, once for each size, but it would save you the hassle of entering a new path and size every time, you would just select the preset from the lightning bolt and hit enter.