It would be useful to have a command/shortcut to repeats your last action. This would save a lot of time in the long run!
Example: You click a tab, eg. Process, then click Level button, then make a specific level adjustment (something you don’t want to save as a preset) and then Apply. Later, you have a different tab open, but you still want to perform the same level adjustment you did in the last action. Instead of having to click back to Process tab and Level button, you just hit a shortcut to Repeat Last Action! This feature exist in many other programs in other program fields, such Blender (Shift-R) for instance.