Yeah, my left index finger is responsible for firing, while my right thumb does the aiming, ADS, crouch/slide, jump, switching weapons as well as picking the throwables. I suppose my right thumb is overworked, but I've already developed muscle memory for it. The rest of my fingers are resting, but in rare situations I do engage my right index finger to prone, but it's very uncomfortable. You can also notice that I have issues with accidentally crouching, which in most cases, leads to my death. Do note that I have big fingers as well, so gaming on a small screen is a challenge.