Ever bit helps and adds up. A brighter lens allows more light in and shallower bokeh. If you are looking for an edge in either case, you buy a brighter lens.

We had similar questions like Are ultra-high ISO sensitivities useful? or even Why do you need image stabilization in a wide-angle lens?. Each is about reaching more, there is always the case where what you have is not enough, so you push the ISO and the aperture or slow down shutter-speed. So, yes, a F/1.2 lens gives you more light but if it's not enough, you may want an F/1. As a side-note, I don't know why we more often see F/0.95 than F/1, seems arbitrary precision or maybe just to say it is faster.

Ever bit helps and adds up. A brighter lens allows more light in and shallower bokeh. If you are looking for an edge in either case, you buy a brighter lens.

We had similar questions like Are ultra-high ISO sensitivities useful? or even Why do you need image stabilization in a wide-angle lens?. Each is about reaching more, there is always the case where what you have is not enough, so you push the ISO and the aperture or slow down shutter-speed. So, yes, a F/1.2 lens gives you more light but if it's not enough, you may want an F/1. As a side-note, I don't know why we more often see F/0.95 than F/1, seems arbitrary precision or maybe just to say it is faster.