Gimp Keyboard Shortcuts
From the Edit > Keyboard Shortcuts menu we can assign a shortcut to almost any action we want. We may have to disable an existing identical shortcut if we want to assing the same key combination. In below example I had disabled ShiftC using Backspace on selecting a new accelerator to then assign ShiftC to Curves... in the Tools section:
Similarly we can assign a shortcut to save our work. By default CtrlS will save a project in Gimps XCF format. In case we had edited another file format and would like to keep it we can assign Overwrite in the File section of the keyboard shortcuts to CtrlS.
Alternatively we can export an image with the default ShiftCtrlE but then we'd have to always press Enter in addition.
Working with shortcuts
By this we can achieve a quite rapid workflow in that we can open multiple files, assign shortcuts to Windows > Next Image, do or work, overwrite the original file by keyboard shortcut above, save it, and lastly CtrlW close that window/tab. As soon as we get used to this it will be a rather quick workflow.