There's a shortcut in Photoshop, that with the brush tool pressing a number sets it's opacity, and with Shift+Number pressed it changes the the Flow. That's great I use this in my workflow all the time.
However, pressing Alt+Number changes the smoothing. And while painting I constatnly press Alt to sample colors and numbers to change opacity. This feature ruins my workflow and I always accidently jump to 100% smoothing and so 😞